Potent Inhibitors of Secretory Phospholipase A2: Synthesis and

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Potent Inhibitors of Secretory Phospholipase A2: Synthesis and Inhibitory Activities of Indolizine and Indene Derivatives Sanji Hagishita,* Masaaki Yamada, Kazuhiro Shirahase, Toshihiko Okada, Yasushi Murakami, Yuji Ito, Takaharu Matsuura, Masaaki Wada, Toshiyuki Kato, Masahiko Ueno, Yukiko Chikazawa, Katsutoshi Yamada, Takashi Ono, Isao Teshirogi, and Mitsuaki Ohtani Shionogi Research Laboratories, Shionogi & Co., Ltd., Fukushima-ku, Osaka 553, Japan Received June 3, 1996X

Phospholipase A2 is an enzyme which hydrolyzes the sn-2 position of certain cellular phospholipids. The liberated lysophospholipid and arachidonic acid are precursors in the biosynthesis of various biologically active products. As human nonpancreatic sPLA2 is present in high levels in the blood of patients in several pathological conditions, the potent sPLA2 inhibitors have been suggested to be useful drugs. Here we describe the synthesis, structureactivity relationship, and inhibitory activities of indolizine and indene derivatives. 1-(Carbamoylmethyl)indolizine derivatives and 1-oxamoylindolizine derivatives exhibited very potent inhibitory activity. The former was unstable to air oxidation, but the latter exhibited an improvement both in stability and in potency. Some compounds approached the stoichiometric limit of the chromogenic assay. Introduction Phospholipase A2 (PLA2) is an enzyme that specifically hydrolyzes the sn-2-acyl ester bond of phosphoglycerides of cell membranes and is distributed widely in nature. Activation of PLA2 leads to the release of fatty acids and lysophospholipid, which are then converted to mediators of inflammation and allergy, such as prostaglandins, leukotrienes, and platelet activating factor.1 Therefore, blockade of PLA2 can result in the suppression of three important classes of lipid mediators and offers an attractive therapeutic approach to inflammation. Over the past decade, a number of distinct types of PLA2 have been isolated and characterized. Pancreatic type I secretory PLA2, nonpancreatic 14-kDa type II secretory PLA2 (sPLA2), and 85-kDa cytosolic PLA22 are especially well-known in relation to pathology. Among these types, mammalian nonpancreatic sPLA2 has been detected in high levels in the blood of patients with septic shock2 and pancreatitis3 and also in the synovial fluid of those suffering from rheumatoid arthritis.4 Because of this involvement of sPLA2 in such inflammatory processes, it has been suggested that a potent sPLA2 inhibitor can be a therapeutically useful drug in the treatment of septic shock, acute respiratory distress syndrome, pancreatitis, trauma, bronchial asthma, allergic rhinitis, rheumatoid arthritis, gout, and other diseases. Various PLA2 inhibitors have been described by many research groups.5 Researchers at Lilly have recently found a highly potent sPLA2 inhibitor6 having a novel indole structure by using computer-aided drug design and chemical modification of a lead compound, which was discovered in the course of high-volume screening. This information prompted us to study the structural effects of the closely related indolizine and indene compounds on sPLA2 activity. The indolizine nucleus is similar to indole with a delocalized 10 π-electron aromatic system. Owing to its electronic and stereoX

Abstract published in Advance ACS Abstracts, August 15, 1996.

S0022-2623(96)00395-0 CCC: $12.00

Figure 1. Prepared compounds.

chemical similarity to indole, the indolizine system was considered likely to show similar sPLA2 inhibitory activity. In this paper, we describe the synthesis and evaluation of sPLA2 inhibitory activity of four types of indolizine derivatives, I-IV, and the indene derivative depicted in Figure 1 (also see Table 1). These derivatives have not only a (carbamoylmethyl) group or an oxamoyl group at the C-1 position but also a carboxylic acid to co-ordinate with the Ca2+ ion located in the hydrophilic domain at the active site. Also chemical modification of the hydrophobic part located in the hydrophobic domain was carried out using SAR study to pursue the effective substituents. Synthesis (1) Synthesis of Type I Compound (Scheme 1). The carbanion of 2-methyl-5-methoxypyridine7 was reacted with benzonitrile to produce 2.8 The © 1996 American Chemical Society

Potent Inhibitors of Secretory Phospholipase A2

Journal of Medicinal Chemistry, 1996, Vol. 39, No. 19 3637

Table 1. Substituents of Indolizine and Indene Derivatives compd 11-15 a b c d 18-20, 25-28, i ii iii iv v vi vii viii ix x xi xii xiii xiv xv xvi xvii xviii xix xx xxi 38-43 a b c d 61-65 a b c d e

R2 Et Et Et Et 31, 32 Et Et Et Et Et cycloPr Me Et Et Et Et Et Et Et Et Et Et Et Et Et Et

R3

compd

R2

R3

Ph o-Ph-C6H4 m-Cl-C6H4 m-Cl-C6H4

e f g

cycloPr Et Et

o-Ph-C6H4 Ph 1-Naphthyl

Ph o-Ph-C6H4 m-Cl-C6H4 m-CF3-C6H4 1-naphthyl o-Ph-C6H4 Ph p-Ph-C6H4 cyclohexyl cyclopentyl cycloheptyl n-Bu pent-4-yl 2-naphthyl 3,5-(t-Bu)2-C6H3 Bn o-Bn-C6H4 2-thienyl 3-(thienyl-2-yl)thienyl-2-yl m-MeO-C6H4 o-NO2-C6H4

xxii xxiii xxiv xxv xxvi xxvii xxviii xxix xxx xxxi xxxii xxxiii xxxiv xxxv xxxvi xxxvii xxxviii xxxix xl xli

Et Me Me cycloPr Et Me cycloPr Me cycloPr iPr tBu cyclopentyl Et Et Et cycloPr OMe SMe Me Me

trans-4-(m-n-pentyl)cyclohexyl 1-adamantyl o-Ph-C6H4 Ph p-n-Bu-C6H4 cyclohexyl cyclopentyl cyclopentyl cyclohexyl o-Ph-C6H4 o-Ph-C6H4 o-Ph-C6H4 m-Ph-C6H4 cinnamyl phenethyl 1-naphthyl o-Ph-C6H4 o-Ph-C6H4 Ph cyclohexyl

Et cycloPr Et Et

Ph o-Ph-C6H4 o-Ph-C6H4 cyclohexyl

e f g

Et Et Et

o-Ph-C6H4 o-Ph-C6H4 o-Ph-C6H4

Me Me Et Et Et

Ph Ph Ph o-Ph-C6H4 o-Bn-C6H4

f g h i j

Et Et Et Et Et

m-Cl-C6H4 o,m-Cl2-C6H3 m-CF3-C6H4 1-naphthyl 2-naphthyl

Scheme 1a

a Reagents: (a) LDA, C H CN; (b) 1-bromo-2-butanone, NaHCO ; (c) LiAlH ; (d) (1) (COCl) , (2) NH OH; (e) BBr ; (f) NaH, 6 5 3 4 2 4 3 Br(CH2)3COOEt; (g) LiOH.

Tschitschibabin reaction, that is, alkylation of the nitrogen of 2 with 1-bromo-2-butanone to the N-alkylated intermediate, followed by cyclization with NaHCO3 gave 3.9 Although indolizine is generally unstable to air oxidation because of its electron-rich character, electron-withdrawing groups on the indolizine nucleus have the effect of making the compounds much less susceptible to oxidation by air. The benzoyl group of 3 was reduced to the benzyl group with LiAlH4 to give compound 4, which was very reactive to an electrophile and was acylated with oxalyl chloride without any catalyst. Sequential treatment with NH4OH gave 5a in excellent yield. Demethylation of 5a with BBr3

yielded 5b, which was O-alkylated using NaH and ethyl 4-bromobutylate to form 6a. (2) Synthesis of Type II Compound (Scheme 2). Compound 710 was reduced by catalytic hydrogenation until no starting material was detected to give a mixture of compounds 8a and 8b. As ammonolysis of 8a gave 9b in poor yield, 8b was used instead to obtain 9a in good yield. The hydroxy group of 9a was protected to give 9b, and then cyclization by the Tschitschibabin reaction was done with 1-bromo-2-butanone and chloromethyl cyclopropyl ketone to obtain 10b accompanied by 10c and 10d, respectively. Ester 8a was also cyclized to furnish 10a. In order to modify the substituent at

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Hagishita et al.

Scheme 2a,b

a Reagents: (a) H , Pd-C: (b) NH OH; (c) BnCl, K CO ; (d) XCH COR , NaHCO ; (e) R COCl; (f) t-BuNH -BH , AlCl ; (g) NaH, 2 4 2 3 2 2 3 3 2 3 3 BrCH2COOR8; (h) LiOH or H2, Pd-C. bR2 and R3 of a-g: see Table 1.

the C-3 position of indolizine, 10 was acylated without any catalyst with various hydrophobic acyl chloride: o-phenylbenzoyl chloride, m-chlorobenzoyl chloride, benzoyl chloride, and 1-naphthyl chloride. Selective reduction of the carbonyl group at the C-3 position of 11, except for 10a, to methylene was carried out with t-BuNH2-BH3 complex and AlCl311 to give 12, which was converted to the desired type II compound 15 as shown in Scheme 2 by deprotection of the benzyl group, followed by alkylation at the C-8 position. (3) Synthesis of Type III Compound (Schemes 3-5). Compound 16b, obtained by O-benzylation of 16a12 was N-alkylated with 1-bromo-2-butanone or bromomethyl cyclopropyl ketone and cyclized by the Tschitschibabin reaction to give 17. Although 17 has an electron-withdrawing group at the indolizine nucleus, the acylation was possible at the C-3 position in good yield without any catalyst, and several acyl chloride were used to vary the R3 group. Hydrolysis of 18 required a drastic condition, using KOH in DMSO at 140 °C. The carboxylic acid was thermally decarboxylated to give 19, which was reduced with LiAlH4 to yield 20. Alternatively, 16b was treated with 3-bromo-4phenyl-2-butanone13 21 under Tschitschibabin reaction conditions to give 22, which was then converted to 20vii, having a methyl group at the C-2 position, by the same procedure cited above. Sequential treatment of 20 with oxalyl chloride and NH4OH formed 25, which was then treated by the same procedure cited for the preparation of 15 to give 28. The merit of this synthetic pathway from 16 to 28 is that the compounds of each step, except for 20, are stable to oxidation by air and can be treated easily. Unfortunately, the starting material 16 is not easily prepared by the reported method.12 We next tried using 3-hydroxypicoline14 23a as a starting material (Scheme 3). Heating the protected compound 23b or 23c with 2-halo ketone compounds

gave an N-alkylated pyridinium intermediate which was cyclized to 24. Various kinds of hydrophobic acyl groups were introduced at the C-3 position of indolizine by this method. Ketone 19 was converted to the desired compounds 28 by the same procedure from 20 or 28. In order to shorten the synthetic steps, the processes of protection and deprotection of the hydroxy group were eliminated (Scheme 4). Hydroxypicoline 23a was Oalkylated with methyl bromoacetate to produce 29, which was cyclized by the same procedure cited above to give 30. To also remove the step of reduction of the carbonyl group at the C-3 position, 30 was treated with various benzyl halides, which gave compounds alkylated at the C-3 position, accompanied by 1,3-dialkylated derivatives. The electrophilic substituent of the indolizine nucleus has been established, and the most reactive positions are the C-3 and C-1 positions, in that order,15 but the difference in reactivities seems to be small. Alternatively, compound 31 was obtained by acylation of 30, followed by selective reduction of the carbonyl group with NaBH4-AlCl3. Although the method required reduction of the newly produced ketone, the yield and procedure for purification of the product were improved. Chemical modification at the C-2 position was achieved with a methoxy or a methylthio group (Scheme 5). Treatment of 16b with excess methyl bromoacetate, followed by cyclization with K2CO3, gave a hydroxy compound that was difficult to isolate and was used directly for the next O-methylation to furnish 17c. Compound 17c was hydrolyzed and decarboxylated thermally to give 24f, which was C-alkylated at the C-3 position with o-(iodomethyl)biphenyl and treated by a procedure similar to that described above to yield 28xxxviii with a methoxy group at the C-2 position. According to the procedure of Kakehi et al.,16 2-benzyloxypyridine 23a was converted to 33, which was also



Scheme 3a,b

a Reagents: (a) NaH, BnCl; (b) XCH COR , NaHCO ; (c) R COCl; (d) (1) KOH-DMSO; (2) 4; (e) LiAlH or NaBH -AlCl ; (f) 16b, 4; 2 8 3 3 4 4 3 (g) BnBr, KOH, TBAB; (h) MeI, K2CO3; (i) (1) (COCl)2, (2) NH4OH (j) H2, Pd-C or BBr3; (k) BrCH2COOMe, K2CO3, KI; (l) OH-. bR2 and R3 of i-xxix: see Table 1.

cyclized to give an ca. 10:1 mixture of 8- and 6-benzyloxy derivatives 34a + 34b. Treatment of the mixture with KOtBu eliminated ethyl acrylate16 to form 35, the isomers of which were separated from each other, and the 6-benzyloxy derivative was then S-alkylated to give 35b. Hydrolysis of 35b with KOH in DMSO under reflux for 8 h formed the dicarboxylic acid, which was thermally decarboxylated to give 24g. Compound 24g was treated with o-phenylbenzyl iodide as above to furnish a C-3 alkylated compound with contamination by a C-1 alkylated compound. Sequential treatment with oxalyl chloride and then NH4OH as above gave 25xxxix, which was separated from the C-1 alkylated derivative. Compound 25xxxix was converted to 28xxxix, having a methylthio group at the C-2 position by the above-mentioned procedure. (4) Synthesis of Type IV Compound (Scheme 6). This type of compound was prepared by applying the second method (Scheme 3) for the preparation of compounds of type III to 4-methoxypicoline 36 to give 41 via several steps as shown in Scheme 6. O-Alkylation of 41 was carried out with ω-bromoalkyl ester, Br(CH2)nCOOEt (n ) 1, 3, and 4), to give 42a-f. In the case of

n ) 2, β-propiolactone17 was used and 43g was obtained. The oxamoyl group of 42 was selectively reduced with t-BuNH2-BH3 complex and AlCl3 to the (carbamoylmethyl) group to give 44a. (5) Synthesis of Amino Derivatives (Scheme 7). Aminopicoline 45a was converted to its N-Cbz derivative 45b, of which the anion was alkylated with methyl bromoacetate to produce 46. Reaction of 46 with 21 or 3-bromo-4-cyclohexyl-2-butanone in the presence of NaHCO3 furnished 32xl or 32xli, which was converted to the desired compound 28 by treatment similar to that described above. The oxamoyl group of 27xli was selectively reduced as in the case of 42 to give 48a. (6) Other Modifications (Scheme 8). Chemical modification at the C-8 position was carried out. Compound 26ii was O-alkylated with alkyl halide to give basic compounds 49c-e and acidic compounds 49b and 49g, following by deprotection. The methylene chain was also changed by addition of β-propiolactone as above. Tetrazole derivative 50b was also prepared via the cyano derivative 50a from 26iii. After the reaction with (COCl)2, 20i was treated with methylamine or dimethylamine instead of NH4OH to

3640


Hagishita et al.

Scheme 4a,b

a Reagents: (a) KOH, BrCH COOMe; (b) (1) XCH COR , (2) DBU; (c) R COCl; (d) NaBH , AlCl ; (e) R CH X; (f) (1) (COCl) , (2) NH OH; 2 2 2 3 4 3 3 2 2 4 (g) OH-. bR2 and R3 of ii, vi, xxiv, and xxx-xxxvii: see Table 1.

Scheme 5a,b

a Reagents: (a) (1) BrCH COOMe, (2) K CO , (3) Me SO , K CO ; (b) (1) KOH-DMSO, (2) 4; (c) (1) BrCH COOEt, NaH, (2) CS , (3) 2 2 3 2 4 2 3 2 2 CH2dCHCOOEt; (d) BrCH2COOEt, DBU; (e) KOtBu; (f) NaH, MeI; (g) o-Ph-Bnl; (h) (1) (COCl)2, (2) NH4OH; (i) H2, Pd-C; (j) BrCH2COOMe, K2CO3, KI; (k) OH-. bR2 and R3 of xxxviii and xxxix: see Table 1.

give mono- or dimethylglyoxylamide, which were then converted to 51a or 51b via a synthetic procedure similar to that cited in the Scheme 3. (7) Synthesis of Indene Derivatives (Scheme 9). To obtain 53, m- or p-anisaldehyde was treated with propionic or butyric anhydride under the Perkin reaction condition. Compound 53 was reduced by catalytic hydrogenation to give 54. Acidic cyclization of 54 yielded 57. Alternatively, the position para to the methoxy group of 54c was blocked by bromination to give 55, which was cyclized to 56 by acidic treatment

and then debrominated using catalytic hydrogenolysis to give 57c. Reaction of 57 with triethyl phosphonoacetate produced 58a and/or 59b,c. Radical bromination of 59b,c gave 60, which on reduction catalytically yielded 58b and 58c. Compound 58 was condensed with benzaldehyde and its derivatives in the presence of MeONa to give 61, which was converted to the amide 62 via the active ester. After demethylation of 62 with BBr3, the compound 63 formed was O-alkylated as above to give 64, which was reduced by catalytic hydrogenation to give 66 and 67.



Scheme 6a,b

a Reagents: (a) (1) XCH COR , (2) DBU; (b) R COCl; (c) t-BuNH -AlCl ; (d) (1) (COCl) , (2) NH OH; (e) BBr ; (f) Br(CH ) COOEt, 2 2 3 2 3 2 4 3 2 n NaH or propiolactone; (g) OH-. bR2 and R3 of 38-43: see Table 1.

Scheme 7a,b

a Reagents: (a) N-(benzyloxycarbonyl)succinimide; (b) NaH, BrCH COOMe; (c) 21 or 3-bromo-4-cyclohexyl-2-butanone, NaHCO ; (d) 2 3 (1) (COCl)2, (2) NH4OH; (e) H2, Pd-C; (f) OH-; (g) (1) t-BuNH2-BH3, AlCl3, (2) H2, Pd-C. bR2 and R3 of xi and xli: see Table 1.

Enzyme Inhibitory Activity and Discussion procedure18

The chromogenic screening assay using a thiol substrate analogue was used to identify and evaluate inhibitors of recombinant human sPLA2. IC50 values of the prepared compounds are shown in Table 2. We also used a slightly modified phosphatidyl choline/deoxycholate assay that had been developed for the evaluation of patient samples of human sPLA2,19,20 and IC50 values are shown in Table 2. As mentioned above, for the structure-activity relationships study, the indolizine derivatives were grouped into four categories according to their structure. Compound 6b of type I did not exceed the micromolar order of inhibitory activity. Compound 12d, bearing the hydroxyl group at the C-8 position, also did not show potent activity. But replacement of the substituent by methylene amide, 15b-g, at this position (type II) had a favorable effect on the enzyme interaction. Crystals of human type II PLA2 complexed with 15f were grown and analyzed by

X-ray crystallography, which will be submitted for publication in due course. However, as mentioned above, these compounds were not stable to air oxidation. Replacing the methylene amide by an oxamoyl group (type III) made the derivative stable and also increased the potency of PLA2 inhibition. Variation of the residue at the C-2 position did not have a major influence on the inhibitory activity. However, bulky substituents such as t-Bu or cyclopentyl groups revealed an unfavorable influence on the ability to inhibit PLA2. The ethyl group appeared to be best. Efforts to optimize compounds of type III included structural variation of the substituent at the C-3 position. Chemical modification giving benzyl-type substituents increased the potency in the following order, depending on the position in the benzene ring: p- < m< o-position (28viii < 28xxxiv < 28ii), although the difference was not statistically important. An electronwithdrawing group, 28iv, seemed to be better than an

3642


Scheme 8a

Hagishita et al.

activity in that order. Introduction of a methyl or a dimethyl group seemed to disturb co-ordination of the amide group with the calcium (51a and 51b). We also examined whether the indolizine skeleton could be replaced by an indene ring. Although indene derivatives 65a-j having an exo-methylene group generally showed 10 times or more decreased potency, compared with the corresponding indolizine derivatives 15b-g, 1-naphthyl derivative (65a) showed an IC50 value of 25 nM. Partially reduced compounds 67a and 67b showed further lower potency. The introduction of an oxamoyl group to the indene ring was tried to improve the activity but was fruitless. The skeleton seems to need an electron-rich character for sPLA2 inhibition, in addition to the geometric 6-5 fused ring. Summary

a

Reagents: (a) R8CH2X, (b) (1) Me3SnN3, (2) HCl.

electron-donating group, 28xx, but compound 28xxi, having a nitro group at the ortho-position, showed lower potency. The electronic effect of the substituent is not a major factor influencing the inhibitory activity. Other benzyl-type compounds, such as 28v, 28xvii, and 28xxvi, showed highly potent activity, and substituted benzyl groups were potent except when the substituent was very bulky (28xv). Elongation of the methylene decreased the activity, as demonstrated by 28xvi, 28xxxv, and 28xxxvi. A 2-fold or greater decrease in potency was observed in compounds with hydrophobic substituents such as alkyl- (28xiii and 28xvi) and cycloalkyl(28ix, 28x and 28xxii) groups. Hydrophobic heteroaromatic substituents (27xviii and 28xix) helped retain the activity. Co-ordination of the substituents at the C-1 and the C-7 or C-8 positions with the calcium ion is necessary to produce the activity as pointed out by the Lilly workers,6 and chemical modification at the C-1 and the C-8 positions of indolizine compounds of type III was achieved. The inhibitory activity disappeared on chemical modification of the ether linkage at the C-8 position to the amino function (28xl), probably due to a conformational change caused by hydrogen bonding between the NH group and the carbonyl group at the C-1 position. The activity was improved by reducing the carbonyl group (28xli) but still the conformation did not seem to be suitable for co-ordination with the calcium, because of the hydrogen bonding of the amino group with the amide group. The tetrazole group provided an additional ligand for the calcium, as shown in 49b and 50b. Pyridine and quinoline rings still may co-ordinate with the calcium (49c, 49d, and 49e), while the compound with a phenyl group (25ii) did not show activity at all. Methylenic homologation with one and two carbon units at the carboxylic acid function of the C-8 position lowered the

In this report, we have described the preparation of indolizine and indene derivatives that are designed to inhibit human nonpancreatic PLA2. 1-(Carbamoylmethyl)indolizine derivatives were potent inhibitors, but were not stable to air oxidation. Introduction of an oxamoyl group to the C-1 position made the derivative stable and highly potent. By chemical modification at the C-3 position with various hydrophobic substituents and at the C-1 or C-8 position with hydrophilic substituents, some compounds approached the stoichiometric limit of the chromogenic assay. Experimental Section General Methods. Melting points were not corrected. IR spectra were recorded on a Nicolet 20SXB FT-IR spectrometer. 1H NMR spectra were recorded on a Varian VXR-200 and VXR300 FT-NMR spectrometer with tetramethylsilane as internal reference. Mass spectra were measured on a JEOL JMS-SX/ S102A or a HITACHI M-90 mass spectrometer. Column chromatography was performed on Merck Kiesel gel 60 with a medium pressure unless otherwise noted. Drying of an organic phase over anhydrous Na2SO4 is simply indicated by the word “dried”. Solvents were removed by evaporation under reduced pressure unless otherwise noted. 5-Methoxy-2-phenacylpyridine (2). A solution of n-BuLi in hexane (1.6 M, 11.4 mL, 18.2 mmol) was added dropwise to a solution of diisopropylamine (1.81 g, 17.9 mmol) in THF (50 mL) at -60 to -70 °C under N2. The mixture was stirred for 10 min. A solution of 5-methoxy-2-methylpyridine7 (2.20 g, 17.9 mmol) in THF (4 mL) was added dropwise. The mixture was stirred for 10 min. A solution of benzonitrile (1.84 g, 17.9 mmol) in THF (8 mL) was added dropwise at -70 °C. The mixture was stirred at -78 °C for 1 h and at room temperature for 2 h and poured to ice-cold aqueous NH4Cl. The organic phase was separated and the aqueous phase was extracted with ether. The combined organic phases were extracted with dilute HCl. The extracts were washed with ether, basified with 10% aqueous NaOH, and extracted with ether. The extracts were washed with water and dried. After removal of the solvent, the residue was chromatographed by eluting with hexane:AcOEt (3:2) and crystallized from benzene:hexane to give 3, 2.32 g (57.0% yield). The NMR showed the product to be a mixture of the keto and the enol tautomers: IR νmax (Nujol) 1685, 1630 cm-1; 1H NMR (CDCl3) δ 3.84-3.88 (3H, m), 4.45 (2H, m), 7.0-7.3 (3H, m), 7.82 (1H, m), 8.07 (2H, m), 8.27 (1H, m). Anal. (C14H13NO2) C, H, N. 1-Benzoyl-2-ethyl-6-methoxyindolizine (3). A mixture of the pyridine derivative 2 (2.146 g, 9.44 mmol), 1-bromo-2butanone (2.14 g, 14.2 mmol), and NaHCO3 (1.60 g, 19 mmol) in acetone (50 mL) was heated under reflux for 20 h. The insoluble materials were removed off by filtration. The filtrate was concentrated. The residue was recrystallized from benzene:hexane to give 3: 2.39 g (90.7% yield); mp 138-139 °C; IR νmax (Nujol) 1600, 1592, 1505 cm-1; 1H NMR (CDCl3) δ 1.19



Scheme 9a,b

a Reagents: (a) (R CO) O, R COONa; (b) H , Pd-C; (c) Br ; (d) PPA; (e) H , Pd-C, AcONa; (f) PPA or TFA; (g) (EtO) POCH COOEt, 2 2 2 2 2 2 2 2 NaH; (h) NBS, BPO; (i) H2, PtO2; (j) RCHO, MeONa; (k) (1) BPO, (2) NH4OH; (l) BBr3; (m) NaH, Br(CH2)nCOOEt; (n) NaOH. bR2 and R3 of 61-65: see Table 1.

(3H, t, J ) 7.5 Hz), 2.72 (2H, q, J ) 7.4 Hz), 3.80 (3H, s), 6.69 (1H, dd, J ) 2.0, 9.8 Hz), 7.10 (1H, s), 7.26 (1H, d, J ) 9.6 Hz), 7.35-7.55 (4H, m), 7.67 (2H, m). Anal. (C14H14NO2) C, H, N. 1-Benzyl-2-ethyl-6-methoxyindolizine (4). The benzoyl derivative 3 (1.37 g, 4.90 mmol) was added in small portions to a slurry of LiAlH4 (1.03 g, 27.1 mmol) in ether (100 mL) with cooling in ice under N2. The mixture was then heated under reflux for 4.5 h. After cooling, the mixture was poured into ice-cold 5% aqueous NaOH and extracted with ether. The extracts were washed with water and dried. The solvent was removed to give 1.23 g (94.5% yield). The oily residue was used in the next preparation without further purification owing to its unstability: IR νmax (film) 1642, 1550, 1218 cm-1; 1H NMR (CDCl ) δ 1.18 (3H, t, J ) 7.6 Hz), 2.57 (2H, q, J ) 3 7.5 Hz), 3.75 (3H, s), 4.06 (2H, s), 6.38 (1H, dd, J ) 9.6, 2.2 Hz), 7.0-7.3 (7H, m), 7.39 (1H, d, J ) 2.2 Hz). (1-Benzyl-2-ethyl-6-methoxyindolizin-3-yl)glyoxylamide (5a). A solution of the indolizine compound 4 (1.288 g, 4.85 mmol) in THF (25 mL) was added dropwise to a solution of (COCl)2 (3.18 g, 25 mmol) in THF (5 mL) with cooling in ice. The mixture was stirred at 0 °C for 1 h and added dropwise to 28% NH4OH (50 mL) with cooling in ice. The mixture was stirred for 1 h at room temperature. Water was added. The mixture was extracted with CH2Cl2. The extracts were washed with water and dried. After removal of the solvent, the residue was crystallized from ethyl acetate:

benzene to give 5a: 1.27 g (73.6% yield); mp 159-160 °C; IR νmax (Nujol) 3342, 3166, 1664, 1571 cm-1; 1H NMR (CDCl3) δ 1.51 (3H, t, J ) 7.4 Hz), 2.90 (2H, q, J ) 7.4 Hz), 3.84 (3H, s), 4.07 (2H, s), 5.83 (1H, br s), 6.55 (1H, br s), 6.96 (1H, dd, J ) 9.4, 2.4 Hz), 7.1-7.3 (6H, m), 9.59 (1H, d, J ) 2.4 Hz). Anal. (C20H20N2O3) C, H, N. (1-Benzyl-2-ethyl-6-hydroxyindolizin-3-yl)glyoxylamide (5b). A solution of BBr3 (976 mg, 3.89 mmol) in CH2Cl2 (5 mL) was added to a solution of the methoxy compound 5a (437 mg, 1.30 mmol) in CH2Cl2 (50 mL) at -20 °C. The mixture was stirred at room temperature for 24 h and poured to ice water. A small amount of MeOH was added. The organic phase was separated and washed with water. After removal of the solvent, The residue was crystallized from CH2Cl2: mp 219-220 °C (dec); IR νmax (Nujol) 3388, 3261, 3193, 1678, 1530 cm-1; 1H NMR (CDCl3:CD3OD) δ 1.14 (3H, t, J ) 7.6 Hz), 2.85 (2H, q, J ) 7.8 Hz), 4.06 (2H, s), 7.01 (1H, dd, J ) 9.4, 2.4 Hz), 7.05-7.25 (6H, m), 9.64 (1H, d, J ) 2.4 Hz). Anal. (C19H18N2O3‚0.9H2O) C, H, N. (1-Benzyl-6-[(3-carbethoxypropyl)oxy]-2-ethylindolizin3-yl)glyoxylamide (6a). NaH (60%, 52 mg, 1.32 mmol) was added to a solution of the alcohol 5b (213 mg, 0.661 mmol) and ethyl 4-bromo-2-butylate (283 mg, 1.45 mmol) in DMF (5 mL) with cooling in ice under N2. The mixture was stirred at room temperature for 8.5 h, poured to ice water and extracted with ethyl acetate. The extracts were washed with water and dried. After removal of the solvent, the residue was chro-

3644


Table 2. Inhibitory Activity against Human sPLA2 and Arachidonic Acida

compd 6b 12d 15b 15c 15e 15f 15g 28i 27ii 28ii 28iii 28iv 28v 28vi 28vii 28viii 28xi 28x 28xi 28xii 28xiii 28xiv 28xv 28xvi 28xvii 28xviii 28xix 28xx 28xxi 28xxii 28xxiii 28xxiv 28xxv 28xxvi 28xxvii 28xxviii 28xxix 28xxx 28xxxi 28xxxii a

IC50 (µM)

IC50 (µM)

chromogenic PC/DOC assay assay

chromogenic PC/DOC assay assay

1.1 19 0.014 0.015 0.013 0.013 0.03 0.008 0.017 0.006 0.006 0.009 0.005 0.009 0.008 0.018 0.021 0.019 0.023 0.062 0.017 0.017 6.6 0.051 0.006 0.011 0.01 0.021 0.036 0.025 0.12 0.008 0.046 0.011 0.01 0.029 0.014 0.043 0.035 0.1

0.014 0.052 0.026 0.028 0.135 0.005 0.003 0.003 0.003 0.024 0.006 0.003 0.013 0.03 0.019 0.1 0.078 0.0073 0.0013 0.013 0.011 0.03 0.12 0.02 0.0014 0.049 0.005 0.015 0.088 0.022 0.16

compd 28xxxiii 28xxxiv 28xxxv 28xxxvi 28xxxvii 28xxxviii 28xxxix 28xl 28xli 43a 43b 43c 43d 43e 43f 43g 44 48b 49b 49c 49d 49e 49g 49h 50b 51a 51b 65a 65b 65c 65d 65e 65f 65g 65h 65i 65j 67a 67b

0.28 0.009 0.038 0.051 0.023 0.015 0.016 >50 >50 0.2 4.4 0.14 3.4 1.4 1.3 0.24 0.08 22 0.007 0.046 0.083 0.055 0.08 0.044 0.03 >50 >50 0.91 0.42 0.16 0.1 0.4 0.2 0.067 0.24 0.025 0.17 15 12

0.0042 0.08 0.2 0.013

0.007

0.21 0.13 0.045

0.42

0.13

IC50 values are the means of at least two experiments.

matographed by eluting with hexane:EtOAc (1:2) and recrystallized from benzene to give 6a: 162 mg (56.2% yield); mp 143-144 °C. Anal. (C25H28N2O5) C, H, N. (1-Benzyl-6-[(3-carboxypropyl)oxy]-2-ethylindolizin-3yl)glyoxylamide (6b). A mixture of the ester 6a (125 mg, 0.286 mmol) in MeOH (1.2 mL) and 10% aqueous LiOH (1.2 mL) was stirred at room temperature for 3 h, acidified with dilute HCl, and extracted with CH2Cl2. The extracts were washed with water and dried. After removal of the solvent at reduced pressure, the residue was chromatographed by eluting with CHCl3:MeOH (10:1) and recrystallized from EtOAc to give 6b: 58.4 mg (49.9% yield); mp 176-178 °C; IR νmax (Nujol) 3391, 3203, 1722, 1663, 1569, 1263 cm-1; 1H NMR (CDCl3) δ 1.14 (3H, t, J ) 7.5 Hz), 2.13 (2H, m), 2.52 (2H, t, J ) 6.9 Hz), 2.87 (2H, q, J ) 7.8 Hz), 4.06 (2H, t, J ) 6.3 Hz), 7.00 (1H, dd, J ) 9.3, 2.1 Hz), 7.05-7.3 (6H, m), 9.78 (1H, d, J ) 1.5 Hz). Anal. (C23H24N2O5‚0.5H2O) C, H, N. Ethyl 3-(3-(Benzyloxy)-2-pyridinyl)propanoate (8a). A mixture of (E)-ethyl 3-(3-(benzyloxy)-2-pyridinyl)propenoate10 (12.2 g, 43.0 mmol), and 10% Pd-C (0.5 g) in EtOAc (250 mL) was stirred in an H2 atmosphere until no more starting material remained. The catalyst was filtered and the filtrate was concentrated. The residue was chromatographed by eluting with hexane:AcOEt (2:1 and 1:2). The fraction with the larger Rf value (6.0 g (48.8% yield)) was the title compound: 1H NMR (CDCl3) δ 1.23 (3H, t, J ) 7.2 Hz), 2.80 (2H, t, J ) 7.5 Hz), 3.22 (2H, t, J ) 8.1 Hz), 4.13 (2H, q, J ) 7.2 Hz), 5.10 (2H, s), 7.07 (1H, dd, J ) 4.5, 8.4 Hz), 7.13 (1H, dd, J ) 1.5, 8.4 Hz), 7.3-7.5 (5H, m), 8.11 (1H, dd, J ) 1.5, 4.5 Hz). The fraction with the smaller Rf value (3.95 g, 47.0% yield) was ethyl 3-(3-hydroxy-2-pyridinyl)propanoate (8b).10

Hagishita et al. 3-(3-Hydroxy-2-pyridinyl)propanamide (9a). A solution of the ester 8b (7.47 g) in 28% NH4OH (50 mL) was allowed to stand at room temperature overnight, and the volatile materials were removed by distillation. The residue was crystallized from EtOAc to give 9a: 6.49 g (94.7% yield); mp 130-134 °C; IR νmax (Nujol) 3292, 3112, 1682, 1632 cm-1; 1H NMR (CDCl3:CD3OD) δ 2.71 (2H, t, J ) 6.9 Hz), 3.06 (2H, t, J ) 6.6 Hz), 7.09 (1H, dd, J ) 4.8, 8.1 Hz), 7.23 (1H, dd, J ) 1.5, 7.8 Hz), 8.00 (1H, dd, J ) 1.2, 4.5 Hz). Anal. (C8H10N2O2) C, H, N. 3-(3-(Benzyloxy)-2-pyridinyl)propanamide (9b). A mixture of the hydroxy compound 9a (4.85 g, 29.2 mmol), benzyl chloride (4.06 g, 32.1 mmol), and K2CO3 (8.07 g, 58.4 mmol) in methyl ethyl ketone (100 mL) was heated under reflux for 9 h. The insoluble materials were removed by filtration. The filtrate was concentrated. The residue was dissolved in CH2Cl2. The solution was washed with water and dried. After removal of the solvent, the residue was crystallized from benzene to give 9b: 5.10 g (68.2% yield); mp 126-127 °C; IR νmax (Nujol) 3412, 3270, 3090, 1665, 1614, 1283 cm-1; 1H NMR (CDCl3) δ 2.75 (2H, t, J ) 6.9 Hz), 3.23 (2H, t, J ) 7.5 Hz), 5.10 (2H, s), 5.34 (1H, br s), 6.54 (1H, br s), 7.10 (1H, dd, J ) 4.2, 8.4 Hz), 7.16 (1H, dd, J ) 8.4, 1.5 Hz), 7.3-7.45 (5H, m), 8.10 (1H, dd, J ) 1.5, 4.5 Hz). Anal. (C15H16N2O2) C, H, N. Ethyl 2-(8-(Benzyloxy)-2-ethylindolizin-1-yl)acetate (10a). A mixture of the ester 8a (1.0 g, 3.51 mmol), 1-bromo2-butanone (0.79 g, 5.23 mmol), and NaHCO3 (0.70 g, 8.23 mmol) in methyl ethyl ketone (10 mL) was heated under reflux for 20 h. The solid was filtered off. After removal of the solvent of the filtrate, the residue was chromatographed by eluting with hexane:AcOEt (5:1) to give 10a (283 mg, 23.9% yield) as an oil: 1H NMR (CDCl3) δ 1.15 (3H, t, J ) 7.2 Hz), 1.25 (3H, t, J ) 7.5 Hz), 2.61 (2H, q, J ) 7.6 Hz), 3.97 (2H, s), 4.04 (2H, q, J ) 7.2 Hz), 5.11 (2H, s), 5.93 (1H, d, J ) 7.4 Hz), 6.23 (1H, t, J ) 7.0 Hz), 7.08 (1H, s), 7.3-7.5 (6H, m). 2-(8-(Benzyloxy)-2-ethylindolizin-1-yl)acetamide (10b) and 2-(2-Ethyl-8-[(2-oxobutyl)oxy]indolizin-1-yl)acetamide (10c). The residue was chromatographed by eluting with hexane:EtOAc (1:2) and with EtOAc. The first fraction was crystallized from benzene:hexane to give 10b: 2.32 g (48.2% yield); mp 117-119 °C; IR νmax (Nujol) 3384, 3188, 1655 cm-1; 1H NMR (CDCl3) δ 1.25 (3H, t, J ) 7.5 Hz), 2.65 (2H, q, J ) 7.4 Hz), 3.87 (2H, s), 5.15 (2H, s), 5.21 (1H, br s), 5.63 (1H, br s), 6.01 (1H, d, J ) 7.4 Hz), 6.29 (1H, t, J ) 7.1 Hz), 7.11 (1H, s), 7.3-7.5 (6H, m). Anal. (C19H20N2O2) C, H, N. The second fraction was crystallized from AcOEt:hexane to give 10c: 0.208 g (4.6% yield); mp 156-157 °C; IR νmax (Nujol) 3390, 3167, 1717, 1682 cm-1; 1H NMR (CDCl3) δ 1.14 (3H, t, J ) 7.3 Hz), 1.28 (3H, t, J ) 7.6 Hz), 2.63 (2H, q, J ) 7.2 Hz), 2.72 (2H, q, J ) 7.6 Hz), 3.92 (2H, s), 4.69 (2H, s), 5.26 (1H, br s), 5.80 (1H, d, J ) 7.2 Hz), 6.26 (1H, t, J ) 7.1 Hz), 6.28 (1H, br s), 7.13 (1H, s), 7.51 (1H, d, J ) 6.8 Hz). Anal (C16H20N2O3‚0.1AcOEt) C, H, N. 2-(8-(Benzyloxy)-2-cyclopropylindolizin-1-yl)acetamide (10d): 30.8% yield; mp 128-131 °C; IR νmax (Nujol) 3386, 3197, 1655 cm-1; 1H NMR (CDCl3) δ 0.54 (1H, dd, J ) 4.2, 1.8 Hz), 0.55 (1H, dd, J ) 3.9, 2.1 Hz), 0.90 (1H, dd, J ) 1.5, 4.2 Hz), 0.93 (1H, dd, J ) 3.2, 2.1 Hz), 4.00 (2H, s), 5.15 (2H, s), 5.22 (1H, br s), 5.65 (1H, br s), 6.00 (1H, d, J ) 7.5 Hz), 6.27 (1H, t, J ) 6.9 Hz), 7.3-7.5 (6H, m). Anal. (C19H18N2O2 0.2C6H6‚0.1H2O) C, H, N. 3-(Substituted benzoyl)indolizine (11). General procedure: the indolizine derivative 10 (1 equiv) and substituted benzoyl chloride (1.5 equiv) in benzene were heated under reflux for 4 h and washed with aqueous NaHCO3 and dried. After removal of the solvent, the residue was purified by recrystallization or column chromatography. Ethyl 2-(8-(Benzyloxy)-2-ethyl-3-(o-phenylbenzoyl)indolizin-1-yl)acetate (11a). Column chromatography (hexane:AcOEt (5:1)) yielded 73.2% of an amorphous solid: IR νmax (Nujol) 1736, 1589, 1545 cm-1; 1H NMR (CDCl3) δ 0.80 (3H, t, J ) 7.4 Hz), 1.08 (3H, t, J ) 7.2 Hz), 2.14 (2H, br s), 3.78 (2H, s), 3.94 (2H, q, J ) 7.0 Hz), 5.10 (2H, s), 6.40 (1H, d, J ) 7.2 Hz), 6.59 (1H, t, J ) 7.3 Hz), 7.1-7.6 (14H, m), 9.32 (1H, d, J ) 6.6 Hz). Anal. (C34H31NO4) C, H, N.



2-(8-(Benzyloxy)-2-ethyl-3-(o-phenylbenzoyl)indolizin1-yl)acetamide (11b). Column chromatography (hexane: AcOEt (1:2)) yielded 71.3% of an amorphous solid: 1H NMR (CDCl3) δ 0.78 (3H, t, J ) 7.5 Hz), 2.05 (2H, br s), 3.65 (2H, br s), 4.82 (1H, br s), 5.06 (1H, br s), 5.14 (2H, s), 6.42 (1H, d, J ) 7.5 Hz), 6.63 (1H, t, J ) 7.5 Hz), 6.95 (3H, m), 7.3-7.65 (11H, m), 9.14 (1H, d, J ) 6.9 Hz). 2-(8-(Benzyloxy)-3-(m-chlorobenzoyl)-2-ethylindolizin1-yl)acetamide (11c): mp 239-240 °C (dec) (benzene); 96.2% yield; IR νmax (Nujol) 3474, 3166, 1680, 1595 cm-1; 1H NMR (CDCl3:CD3OD) δ 0.90 (3H, t, J ) 7.6 Hz), 2.32 (2H, q, J ) 7.5 Hz), 3.84 (2H, s), 5.21 (2H, s), 6.54 (1H, d, J ) 7.8 Hz), 6.70 (1H, t, J ) 7.2 Hz), 7.35-7.6 (8H, m), 9.15 (1H, d, J ) 7.0 Hz). 2-(3-(m-Chlorobenzoyl)-2-ethyl-8-[(2-oxobutyl)oxy]indolizin-1-yl)acetamide (11d): mp 191-192 °C (AcOEt:benzene); 68.4% yield; IR νmax (KBr) 1725, 1668, 1385 cm-1; 1H NMR (CDCl3) δ 0.96 (3H, t, J ) 7.4 Hz), 1.18 (3H, t, J ) 7.2 Hz), 2.44 (2H, q, J ) 7.3 Hz), 2.61 (2H, q, J ) 7.4 Hz), 3.94 (2H, s), 4.81 (2H, s), 5.25 (1H, br s), 6.30 (1H, d, J ) 7.4 Hz), 6.49 (1H, br s), 6.65 (1H, t, J ) 7.3 Hz), 7.35-7.6 (3H, m), 7.64 (1H, m), 9.16 (1H, d, J ) 6.6 Hz). Anal. (C22H23ClN2O4‚0.1C6H6) C, H, Cl, N. 2-(8-(Benzyloxy)-2-cyclopropyl-3-(o-phenylbenzoyl)indolizin-1-yl)acetamide (11e). Column chromatography (hexane:AcOEt (1:2)) yielded 56.6% of an amorphous solid. 3-(Substituted benzyl)indolizine (12). General procedure: BH3-t-BuNH2 complex (6 equiv) was added in small portions to a mixture of pulverized AlCl3 (3 equiv) in CH2Cl2 with cooling in ice. After stirring for 10 min, the mixture became clear. A solution of the ketone 11 (1 equiv) in CH2Cl2 was added dropwise to the solution. The reddish orange solution was stirred for 5 h. Dilute HCl was added dropwise. The organic phase was separated, washed with aqueous NaHCO3 and water successively, and dried. After removal of the solvent, the residue was purified by chromatography or recrystallization. 2-(8-(Benzyloxy)-2-ethyl-3-(o-phenylbenzoyl)indolizin3-yl)ethanol (12a). Column chromatography (hexane:AcOEt (1:1)) gave viscous oil in 45.1% yield: 1H NMR (CDCl3) δ 1.09 (3H, t, J ) 7.6 Hz), 2.61 (2H, q, J ) 7.5 Hz), 3.16 (2H, t, J ) 6.9 Hz), 3.73 (2H, q, J ) 6.3 Hz), 4.10 (2H, s), 5.11 (2H, s), 5.94 (1H, d, J ) 7.5 Hz), 6.16 (1H, t, J ) 7.2 Hz), 6.66 (1H, d, J ) 7.8 Hz), 6.91 (1H, d, J ) 7.2 Hz), 7.1-7.6 (13H, m). 2-(8-(Benzyloxy)-2-ethyl-3-(o-phenylbenzyl)indolizin1-yl)acetamide (12b): mp 134-136 °C (benzene:hexane); 59.7% yield; IR νmax (Nujol) 3451, 3171, 1677, 1526, 1259 cm-1; 1H NMR (CDCl ) δ 1.10 (3H, t J ) 7.5 Hz), 2.63 (2H, q, J ) 3 7.8 Hz), 3.92 (2H, s), 4.11 (2H, s), 5.13 (2H, s), 5.20 (1H, br s), 5.65 (1H, br s), 5.99 (1H, d, J ) 7.5 Hz), 6.19 (1H, t, J ) 7.1 Hz), 6.67 (1H, d, J ) 7.5 Hz), 6.92 (1H, d, J ) 7.2 Hz), 7.13 (1H, dt, J ) 1.8, 7.2 Hz), 7.2-7.5 (12H, m). Anal. (C32H30N2O2) C, H, N. 2-(8-(Benzyloxy)-3-(m-chlorobenzyl)-2-ethylindolizin1-yl)acetamide (12c): mp 167-168 °C (benzene:hexane); 69.7% yield; IR νmax (Nujol) 3389, 3191, 1650, 1527 cm-1; 1H NMR (CDCl3) δ 1.15 (3H, t J ) 7.6 Hz), 2.70 (2H, q, J ) 7.6 Hz), 3.94 (2H, s), 4.20 (2H, s) 5.16 (2H, s), 5.19 (1H, br s), 5.69 (1H, br s), 6.05 (1H, d, J ) 7.2 Hz), 6.27 (1H, t, J ) 7.1 Hz), 6.88 (1H, t, J ) 4.4 Hz), 7.05 (1H, s), 7.1-7.25 (3H, m), 7.37.5 (5H, m). Anal (C26H25ClN2O2) C, H, Cl, N. 2-(3-(m-Chlorobenzyl)-2-ethyl-8-(2-hydroxybutyloxy)indolizin-1-yl)acetamide (12d): mp 131 °C (benzene:hexane); 73.0% yield; IR νmax (Nujol) 3378, 3185, 1656, 1527 cm-1; 1H NMR (CDCl ) δ 1.05 (3H, t J ) 7.5 Hz), 1.16 (3H, t, J ) 7.5 3 Hz), 1.64 (2H, m), 2.70 (2H, q, J ) 7.8 Hz), 3.8-4.05 (5H, m), 4.20 (2H, s), 5.55 (1H, br s), 5.68 (1H, br s), 5.93 (1H, d, J ) 7.2 Hz), 6.30 (1H, t, J ) 7.2 Hz), 6.88 (1H, m), 7.04 (1H, s), 7.1-7.2 (3H, m). Anal. (C23H27ClN2O3) C, H, Cl, N. 2-(8-(Benzyloxy)-2-cyclopropyl-3-(o-phenylbenzyl)indolizin-1-yl)acetamide (12e): mp 208-210 °C (benzene); 37.9% yield. Anal. (C33H30N2O2) C, H, N. 2-(3-Benzyl-8-(benzyloxy)-2-ethylindolizin-1-yl)acetamide (12f): mp 174-176 °C (ether:hexane); 77.3% yield. Anal. (C26H26N2O2) C, H, N.

2-(3-Naphthyl-8-(benzyloxy)-2-ethylindolizin-1-yl)acetamide (12g): mp 166-169 °C (dec) (ether:hexane); 43.5% yield. Anal. (C30H28N2O2) C, H, N. 8-Hydroxyindolizine Compounds (13). General procedure: A mixture of the 8-(benzyloxy)indolizine derivative 12 and 10% Pd-C in EtOAc was stirred in hydrogen for 9h to 3 d. 2-(2-Ethyl-8-hydroxy-3-(o-phenylbenzyl)indolizin-1yl)acetamide (13b): amorphous solid; 59.6% yield; 1H NMR (CDCl3:CD3OD) δ 1.10 (3H, t, J ) 7.5 Hz), 2.63 (2H, q, J ) 7.5 Hz), 3.89 (2H, s), 4.10 (2H, s), 5.84 (1H, d, J ) 7.2 Hz), 6.18 (1H, t, J ) 7.1 Hz), 6.67 (1H, d, J ) 7.6 Hz), 6.88 (1H, d, J ) 6.8 Hz), 7.1-7.55 (8H, m). 2-(3-(m-Chlorobenzyl)-2-ethyl-8-hydroxyindolizin-1yl)acetamide (13c): amorphous solid; 58.3% yield. 2-(2-Cyclopropyl-8-hydroxy-3-(o-phenylbenzyl)indolizin-1-yl)acetamide (13e): amorphous solid; 55.8% yield. 2-(3-Benzyl-8-hydroxy-2-ethylindolizin-1-yl)acetamide (13f): mp 138-141 °C (ether:hexane); 45% yield. Anal. (C19H20N2O2) C, H, N. 2-(3-Naphthyl-8-hydroxy-2-ethylindolizin-1-yl)acetamide (13g): mp 138-142 °C (powder) (ether-hexane:AcOEt). 32% yield. (Indolizin-8-yloxy)acetate Compounds (14 and 15). General procedure: 60% NaH (1.5 equiv) was added in small portions to a mixture of the 8-hydroxyindolizine compound 13 (1.0 equiv) and benzyl, ethyl, or methyl bromoacetate (3.0 equiv) in DMF. The mixture was stirred at room temperature for 4-10 h. Dilute HCl was added. The mixture was extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvent, the residue was purified by chromatography or recrystallization. 2-(8-[[(Benzyloxycarbonyl)methyl]oxy]-2-ethyl-3-(ophenylbenzyl)indolizin-1-yl)acetamide (14b) and carboxylic acid 15b: amorphous solid; 45.4% yield. 15b: mp 164-165 °C (AcOEt); 61.1% yield; IR νmax (Nujol) 3410, 3228, 1732, 1666, 1603, 1265 cm-1; 1H NMR (CDCl3: CD3OD) δ 1.12 (3H, t, J ) 7.5 Hz), 2.69 (2H, q, J ) 7.5 Hz), 3.95 (2H, s), 4.11 (2H, s), 4.67 (2H, s), 5.86 (1H, d, J ) 7.2 Hz), 6.18 (2H, t, J ) 7.2 Hz) 6.67 (1H, d, J ) 7.5 Hz), 6.93 (1H, d, J ) 6.9 Hz), 7.12 (1H, m), 7.2-7.3 (2H, m), 7.3-7.5 (5H, m). Anal. (C27H26N2O4‚1.4H2O) C, H, N. 2-(8-[[(Benzyloxycarbonyl)methyl]oxy]-3-(m-chlorobenzyl)-2-ethylindolizin-1-yl)acetamide (14c) and carboxylic acid 15c: mp 157-158 °C (benzene); 38.8% yield. 15c: mp 216-219 °C (dec) (AcOEt); 57.5% yield; IR νmax (KBr) 3416, 3311, 1739, 1707, 1643, 1620, 1572, 1552, 1529, 1255 cm-1; 1H NMR (CDCl3:CD3OD) δ 1.16 (3H, t, J ) 7.5 Hz), 2.76 (2H, q, J ) 7.5 Hz), 3.98 (2H, s), 4.21 (2H, s), 4.70 (2H, s), 5.92 (1H, d, J ) 7.5 Hz), 6.27 (1H, t, J ) 6.9 Hz), 6.89 (1H, t, J ) 4.2 Hz), 7.04 (1H, s), 7.17 (3H, m). Anal. (C21H21ClN2O4‚0.1H2O) C, H, Cl, N. 2-(8-[(Carbomethoxymethyl)oxy]-2-cyclopropyl-3-(ophenylbenzyl)indolizin-1-yl)acetamide (14e) and carboxylic acid 15e: amorphous solid; 43.8% yield. 15e: 65.5% yield; 1H NMR (CDCl3) δ 0.51 (2H, m), 0.89 (2H, m), 1.76 (1H, m), 4.06 (2H, s), 4.22 (2H, s), 4.63 (2H, s), 5.82 (1H, d, J ) 7.5 Hz), 6.16 (1H, t, J ) 7.2 Hz), 6.56 (1H, d, J ) 7.5 Hz), 6.88 (1H, d, J ) 7.2 Hz), 7.11 (1H, dt, J ) 7.5, 1.5 Hz), 7.26 (2H, m), 7.3-7.5 (5H, m). Methyl ((3-benzyl-1-(carbamoylmethyl)-2-ethylindolizin-8-yl)oxy)acetate (14f) and carboxylic acid 15f: mp 159-163 °C (ether:hexane); 42.2% yield. Anal. (C22H24N2O4‚0.2H2O) C, H, N. 15f: mp 213-218 °C (dec) (ether:hexane); 79% yield; IR νmax (Nujol) 3418, 1735, 1718, 1638, 1618 cm-1; 1H NMR (CDCl3: CD3OD 7:1) δ 1.16 (3H, t, J ) 7.7 Hz), 2.77 (2H, q, J ) 7.7 Hz), 3.99 (2H, s), 4.24 (2H, s), 4.69 (2H, s), 5.89 (1H, d, J ) 7.0 Hz), 6.23 (1H, t, J ) 7.0 Hz), 7.01-7.25 (6H, m). Anal. (C21H22N2O4‚0.2H2O) C, H, N. Methyl ((3-naphthyl-1-(carbamoylmethyl)-2-ethylindolizin-8-yl)oxy)acetate (14g) and carboxylic acid 15g: amorphous solid; 38% yield; IR νmax (CHCl3) 3498, 3384, 1754, 1671, 1596 cm-1; 1H NMR (CDCl3) δ 1.13 (3H, t, J ) 7.4 Hz), 2.77 (2H, q, J ) 7.4 Hz), 3.85 (3H, s), 4.04 (2H, s), 4.64 (2H, s), 4.75 (2H, s), 5.37 (1H, br s), 5.84 (1H, d, J ) 7.2 Hz), 6.18

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(1H, t, J ) 7.2 Hz), 6.54 (1H + 1H, br s + d, J ) 7.2 Hz), 7.06 (1H, d, J ) 6.9 Hz), 7.19-7.27 (1H, m), 7.55-7.63 (2H, m), 7.71 (1H, d, J ) 7.8 Hz), 7.91 (1H, d, J ) 8.1 Hz), 8.24 (1H, d, J ) 8.1 Hz). 15g: mp 129-133 °C (hexane:AcOEt); 65% yield; IR νmax (Nujol) 3198, 1729, 1672, 1599, 1527 cm-1; 1H NMR (CDCl3: CD3OD 7:1) δ 1.12 (3H, t, J ) 7.6 Hz), 2.76 (2H, q, J ) 7.6 Hz), 4.03 (2H, s), 4.65 (2H, s), 4.73 (2H, s), 5.92 (1H, d, J ) 7.6 Hz), 6.21 (1H, t, J ) 7.0 Hz), 6.54 (1H, d, J ) 6.8 Hz), 7.08 (1H, d, J ) 7.6 Hz), 7.23 (1H, t, J ) 7.0 Hz), 7.56-7.65 (2H, m), 7.73 (1H, d, J ) 7.6 Hz), 7.92 (1H, d, J ) 7.4 Hz), 8.25 (1H, d, J ) 9.0 Hz). Ethyl 3-Hydroxy-2-pyridineacetate (16b). NaH (60%, 2.69 g, 66.2 mmol) was added in small portions to a solution of ethyl 3-hydroxy-2-pyridineacetate (16a) (12.0 g, 66.2 mmol)12 in DMF (220 mL) at 0 °C. The mixture was stirred at 0 °C for 50 min. Benzyl chloride (8.4 mL, 72.8 mmol) was added dropwise to the mixture, which was stirred overnight. EtOAc was added. The mixture was washed with 5% aqueous NaHCO3 and water and dried. After removal of the solvent, the residue was chromatographed by eluting with AcOEt: toluene (1:19 to 1:1) to give 16b (16.17 g, 90.0% yield) as an oil: IR νmax (film) 1736, 1446, 1278 cm-1; 1H NMR (CDCl3) δ 1.21 (3H, t, J ) 7.2 Hz), 3.93 (2H, s), 4.14 (2H, q, J ) 7.2 Hz), 5.10 (2H, s), 7.13-7.22 (2H, m), 7.32-7.43 (5H, m), 8.16 (1H, dd, J ) 4.0, 3.0 Hz). Anal. (C16H17NO3) C, H, N. Ethyl 8-(Benzyloxy)-2-ethylindolizine-1-carboxylate (17a). A mixture of pyridine derivative 16b (15.15 g, 55.8 mmol), NaHCO3 (23.45 g, 279 mmol), and 1-bromo-2-butanone (11.4 mL, 113 mmol) in methyl ethyl ketone (250 mL) was heated under reflux for 24 h, washed with water, and dried. After removal of the solvent, The residue was chromatographed by eluting with AcOEt:hexane (1:19 to 1:9) to give 17a (16.66 g, 92.0% yield) as an oil. Anal. (C20H21NO3‚0.1H2O) C, H, N. Ethyl 8-(benzyloxy)-2-cyclopropylindolizine-1-carboxylate (17b): oil; 78% yield; IR νmax (film) 1693, 1525, 1304, 1227, 1094, 753 cm-1; 1H NMR (CDCl3) δ 0.55-0.62 (2H, m), 0.89-0.94 (2H, m), 1.16 (3H, t, J ) 7.2 Hz), 2.14-2.26 (1H, m), 4.14 (2H, q, J ) 7.2 Hz), 5.16 (2H, s), 6.21 (1H, d, J ) 7.5 Hz), 6.43 (1H, t, J ) 7.2 Hz), 6.87 (1H, s), 7.28-7.42 (3H, m), 7.45-7.52 (3H, m). Anal. (C21H21NO3‚0.1H2O) C, H, N. Ethyl 8-(Benzyloxy)-2-ethyl-3-(substituted benzoyl)indolizine-1-carboxylate (18). General procedure: A mixture of the indolizine 17 (1 equiv), substituted benzoyl chloride (2.0 equiv), and Et3N (5.0 equiv) was heated at 90 °C (bath temperature) for 2-8h. EtOAc was added. The mixture was washed with dilute HCl and water and dried. After removal of the solvent, the residue was chromatographed by eluting with AcOEt:hexane (1:2) and recrystallized. Ethyl 3-benzoyl-8-(benzyloxy)-2-ethylindolizine-1-carboxylate (18i): mp 124-125 °C (AcOEt:hexane); 79% yield; IR νmax (KBr) 2969, 1593, 1571, 1552, 1326, 1275, 1045 cm-1; 1H NMR (CDCl ) δ 0.93 (3H, t, J ) 5.0 Hz), 1.12 (3H, t, J ) 3 4.8 Hz), 2.43 (2H, q, J ) 5.0 Hz), 4.03 (2H, q, J ) 4.8 Hz), 5.18 (2H, s), 6.57 (1H, s, J ) 5.0 Hz), 6.72 (1H, dd, J ) 5.0 Hz), 7.3-7.6 (8H, m), 7.55-7.7 (2H, m), 8.99 (1H, d, J ) 4.8 Hz); EIMS m/z 427 [M+]. Anal. (C27H25NO4‚0.1H2O) C, H, N. Ethyl 8-(benzyloxy)-2-ethyl-3-(o-phenylbenzoyl)indolizine-1-carboxylate (18ii): mp 110-112 °C (ether:hexane); 46.0% yield. Anal. (C33H29NO4) C, H, N. Ethyl 8-(benzyloxy)-3-(m-chlorobenzoyl)-2-ethylindolizine-1-carboxylate (18iii): mp 115.0-116.5 °C (ether: hexane); 92% yield. Anal. (C27H24NO4Cl) C, H, N, Cl. Ethyl 8-(benzyloxy)-2-ethyl-3-(m-(trifluoromethyl)benzoyl)indolizine-1-carboxylate (18iv): mp 129.0-129.5 °C (ether:hexane); 82% yield. Anal. (C28H24NO4F3) C, H, N, F. Ethyl 8-(benzyloxy)-2-ethyl-3-(1-naphthoyl)indolizine1-carboxylate (18v): mp 169-170 °C (benzene:hexane); 59.3% yield. Anal. (C31H27NO4) C, H, N. Ethyl 8-(benzyloxy)-2-cyclopropyl-3-(o-phenylbenzoyl)indolizine-1-carboxylate (18vi): mp 143-145 °C (AcOEt: hexane); 52% yield. Anal. (C34H29NO4) C, H, N. 8-(Benzyloxy)-2-ethyl-3-(substituted benzoyl)indolizine-1-carboxylic Acid and 8-(Benzyloxy)-2-ethyl-3-(sub-

stituted benzoyl)indolizine (19). General procedure: To a solution of the ester 18 (1.0 mmol) in DMSO (10 mL) was added 50% aqueous KOH (3 mL). The mixture was heated at 140 °C for 2-24 h. After cooling, the mixture was acidified with dilute HCl and extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvent, the residue was purified by recrystallization to give the carboxylic acid. The acid in toluene was heated under reflux for 1 h and the solvent was removed by distillation. The residue was purified by recrystallization. 3-Benzoyl-8-(benzyloxy)-2-ethylindolizine (19i): mp 9293 °C (AcOEt:hexane); IR νmax (KBr) 2965, 1593, 1571, 1552, 1326, 1275, 1045 cm-1; 1H NMR (CDCl3) δ 1.05 (3H, t, J ) 7.4 Hz), 2.42 (2H, q, J ) 7.4 Hz), 5.21 (2H, s), 6.47 (1H, d, J ) 7.4 Hz), 6.62-6.71 (2H, m), 7.25-7.52 (8H, m), 7.61-7.65 (2H, m), 9.23 (1H, d, J ) 7.2 Hz); EIMS m/z 355 [M+]. Anal. (C24H21NO2‚0.1H2O) C, H, N. 8-(Benzyloxy)-2-ethyl-3-(o-phenylbenzoyl)indolizine (19ii): quantitative yield. Anal. (C30H25NO2‚0.1H2O) C, H, N. 8-(Benzyloxy)-3-(m-chlorobenzoyl)-2-ethylindolizine (19iii). mp 95.5-96.5 °C (ether:hexane); 87% yield. Anal. (C24H20NO2Cl) C, H, N, Cl. 8-(Benzyloxy)-2-ethyl-3-(m-(trifluoromethyl)benzoyl)indolizine (19iv): mp 97-98 °C (ether:hexane); 84% yield. Anal. (C25H20NO2F3) C, H, N, F. 8-(Benzyloxy)-2-ethyl-3-(1-naphthoyl)indolizine (19v): amorphous solid; 66.1% yield. 8-(Benzyloxy)-2-cyclopropyl-3-(o-phenylbenzoyl)indolizine (19vi): amorphous solid; 82% yield. Anal. (C31H25NO2 0.1H2O) C, H, N. 8-(Benzyloxy)-3-(substituted methyl)-2-ethylindolizine (20). General procedure: (1) these compound were prepared from 19, according to the procedure described for the preparation of 4 from 3. (2) A mixture of 19, NaBH4 (5 molar equiv), and pulverized AlCl3 (3 molar equiv) in THF was heated under reflux for 45 min. Ice water was added. The mixture was extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvent, the residue was purified by recrystallization or column chromatography. 3-Benzyl-8-(benzyloxy)-2-ethylindolizine (20i): 1H NMR (CDCl3) δ 1.28 (3H, t, J ) 7.4 Hz), 2.71 (2H, q, J ) 7.4 Hz), 4.22 (2H, s), 5.16 (2H, s), 5.99 (1H, d, J ) 7.4 Hz), 6.24 (1H, dd, J ) 7.4, 7.4 Hz), 6.61 (1H, s), 7.02-7.51 (11H, m). 8-(Benzyloxy)-2-ethyl-3-(o-phenylbenzyl)indolizine (20ii): quantitative yield; IR νmax (CHCl3) 1525, 1259 cm-1; 1H NMR (CDCl ) δ 1.25 (3H, t, J ) 7.5 Hz), 2.64 (2H, q, J ) 3 7.5 Hz), 4.12 (2H, s), 5.15 (2H, s), 5.97 (1H, d, J ) 7.2 Hz), 6.20 (1H, t, J ) 7.1 Hz), 6.57 (1H, s), 6.69 (1H, d, J ) 7.4 Hz), 6.94 (1H, d, J ) 6.8 Hz), 7.06-7.55 (13H, m). 8-(Benzyloxy)-3-(m-chlorobenzyl)-2-ethylindolizine (20iii): quantitative yield; IR νmax (CHCl3) 1551, 1258 cm-1; 1H NMR (CDCl ) δ 1.29 (3H, t, J ) 7.5 Hz), 2.70 (2H, q, J ) 3 7.5 Hz), 4.20 (2H, s), 5.18 (2H, s), 6.03 (1H, d, J ) 7.5 Hz), 6.28 (1H, t, J ) 7.1 Hz), 6.61 (1H, s), 6.88-6.93 (1H, m), 7.06 (1H, br s), 7.19-7.23 (3H, m), 7.29-7.53 (5H, m). 8-(Benzyloxy)-2-ethyl-3-(m-(trifluoromethyl)benzyl)indolizine (20iv): mp 73-75 °C (hexane); quantitative yield; IR νmax (Nujol) 1332, 1163, 1114 cm-1; 1H NMR (CDCl3) δ 1.29 (3H, t, J ) 7.5 Hz), 2.71 (2H, q, J ) 7.5 Hz), 4.28 (2H, s), 5.18 (2H, s), 6.03 (1H, d, J ) 7.5 Hz), 6.29 (1H, t, J ) 7.2 Hz), 6.62 (1H, s), 7.09-7.18 (2H, m), 7.30-7.54 (8H, m). 8-(Benzyloxy)-2-ethyl-3-(1-naphthylmethyl)indolizine1-carboxylate (20v): mp 119-120 °C (hexane); 89.0% yield; IR νmax (Nujol) 1530, 1263, 735 cm-1; 1H NMR (CDCl3) δ 1.26 (3H, t, J ) 7.5 Hz), 2.69 (2H, q, J ) 7.2 Hz), 4.65 (2H, s), 5.20 (2H, s), 6.03 (1H, d, J ) 7.2 Hz), 6.23 (1H, t, J ) 6.9 Hz), 6.59 (1H, d, J ) 6.9 Hz), 6.68 (1H, s), 7.10 (1H, d, J ) 6.9 Hz), 7.21 (1H, d, J ) 7.8 Hz), 7.3-7.65 (7H, m), 7.71 (1H, d, J ) 8.4 Hz), 7.91 (1H, d, J ) 8.1 Hz), 8.25 (1H, d, J ) 8.1 Hz). Anal. (C28H25NO‚0.2H2O) C, H, N. 8-(Benzyloxy)-2-cyclopropyl-3-(o-phenylbenzyl)indolizine (20vi): 91% yield; IR νmax (CHCl3) 1527, 1448, 1259 cm-1; 1H NMR (CDCl3) δ 0.64-0.72 (2H, m), 0.83-0.93 (2H,



m), 1.85 (1H, tt, J ) 8.6 Hz, 5.0 Hz), 4.24 (2H, s), 5.13 (2H, s), 5.96 (1H, d, J ) 7.2 Hz), 6.19 (1H, t, J ) 7.2 Hz), 6.27 (1H, s), 6.80 (1H, d, J ) 7.5 Hz), 6.91 (1H, d, J ) 7.2 Hz), 7.14 (1H, td, J ) 7.5 Hz, 2.1 Hz), 7.19-7.52 (12H, m). Ethyl 3-benzyl-8-(benzyloxy)-2-methylindolizine-1carboxylate (22): A mixture of 3-bromo-4-phenyl-butan-2one13 (1.3 equiv), ethyl pyridine-2-acetate (1.0 equiv), and NaHCO3 (10 equiv) was heated at 165 °C for 1-4 h and chromatographed by eluting with hexane:AcOEt (5-2:1): mp 117-118 °C (hexane); 47.4% yield; IR νmax (Nujol) 1707, 1535, 1233 cm-1; 1H NMR (CDCl3) δ 1.15 (3H, t, J ) 7.5 Hz), 2.43 (3H, s), 4.13 (2H, q, J ) 7.2 Hz), 4.22 (2H, s), 5.16 (2H, s), 6.23 (1H, d, J ) 7.5 Hz), 6.39 (1H, t, J ) 6.6 Hz), 7.06 (2H, m), 7.15-7.45 (7H, m), 7.48 (2H, m). Anal. (C26H25NO3) C, H, N. 3-Benzyl-8-(benzyloxy)-2-methylindolizine-1-carboxylic acid: mp 132 °C (dec); 68.4% yield; IR νmax (Nujol) 3295, 1670, 1535, 1259 cm-1; 1H NMR (CDCl3) δ 2.63 (3H, s), 4.25 (2H, s), 5.33 (2H, s), 6.51 (1H, d, J ) 0.8 Hz), 6.53 (1H, s), 7.0-7.1 (2H, m), 7.15-7.3 (2H, m), 7.35-7.50 (6H, m). Anal. (C24H21NO3) C, H, N. 3-Benzyl-8-(benzyloxy)-2-methylindolizine (20vii): quantitative yield; 1H NMR (CDCl3) δ 2.34 (3H, s), 4.22 (2H, s), 5.17 (2H, s) 6.00 (1H, d, J ) 7.6 Hz), 6.25 (1H, t, J ) 7.1 Hz), 6.56 (1H, s), 7.0-7.5 (11H, m). 3-(Benzyloxy)-2-methylpyridine (23b). A mixture of 2-methyl-3-pyridinol 23a14 (16.4 g, 0.15 mol), pulverized KOH (12.72 g, 0.195 mol), tetrabutylammonium bromide (2.42 g, 7.5 mmol), and benzyl bromide (18.7 mL, 0.158 mol) in THF (380 mL) was stirred at room temperature for 1.5 h. Water was added. The mixture was concentrated and then extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvent, 28.3 g (90% yield) of the title compound was obtained: 1H NMR (CDCl3) δ 2.56 (3H, s), 5.11 (2H, s), 7.04-7.16 (2H, m), 7.35-7.45 (5H, m), 8.08 (1H, dd, J ) 4.5, 1.5 Hz). 8-(Benzyloxy)-2-ethylindolizine (24a). A mixture of 23b (29.7 g, 0.149 mol) in EtOAc (17 mL) and 1-bromo-2-butanone (22.5 g, 0.149 mol) was stirred at 70 °C for 0.5 h. EtOAc (23 mL) was added to the reaction mixture and the solid was recrystallized from EtOAc to give the quaternary salt (47.04 g, 90.1%). The quaternary salt (47.04 g, 0.134 mol) in benzene (150 mL) and DBU (44.2 mL, 0.295 mol) were refluxed for 0.75 h, poured into ice water, and extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvent, the title oily compound (46a) (26.62 g, 79% yield) was obtained: 1H NMR (CDCl3) δ 1.28 (3H, t, J ) 7.6 Hz), 2.70 (2H, q, J ) 7.6 Hz), 5.16 (2H, s), 5.99 (1H, d, J ) 7.5 Hz), 6.29 (1H, t, J ) 7.1 Hz), 6.48 (1H, s), 7.10-7.52 (7H, m). 8-(Benzyloxy)-2-methylindolizine (24b): 92% yield; oil; 1 H NMR (CDCl3) δ 2.31 (3H, s), 5.16 (2H, s), 5.98 (1H, d, J ) 7.6 Hz), 6.28 (1H, t, J ) 7.0 Hz), 6.44 (1H, s), 7.08 (1H, s), 7.34-7.55 (6H, m). 2-Cyclopropyl-8-methoxyindolizine (24c): 72% yield; 1H NMR (CDCl3) δ 0.60-0.68 (2H, m), 0.86-0.96 (2H, m), 1.831.97 (1H, m), 3.89 (3H, s), 5.92 (1H, d, J ) 7.4 Hz), 6.25-6.34 (1H + 1H, m), 7.11 (1H, d, J ) 1.6 Hz), 7.47 (1H, d, J ) 7.0 Hz). 8-(Benzyloxy)-2-cyclopropylindolizine (24d): 69% yield; 1 H NMR (CDCl3) δ 0.61-0.69 (2H, m), 0.86-0.96 (2H, m), 1.84-1.97 (1H, m), 5.15 (2H, s), 5.98 (1H, d, J ) 7.6 Hz), 6.256.32 (1H + 1H, m), 7.12 (1H, d, J ) 2.0 Hz), 7.35-7.49 (6H, m). 8-(Benzyloxy)-2-ethyl-3-(substituted carbonyl)indolizine (19). General procedure: This compound was prepared from 24, according to the procedure described for the preparation of 11 from 10. 8-(Benzyloxy)-2-ethyl-3-(p-phenylbenzoyl)indolizine (19viii): mp 114-115 °C; 80% yield. 8-(Benzyloxy)-3-(cyclohexylcarbonyl)-2-ethylindolizine (19ix): mp 88-89 °C (hexane:EtOAc); 77% yield. Anal. (C24H27NO2‚0.1H2O) C, H, N. 8-(Benzyloxy)-3-(cyclopentylcarbonyl)-2-ethylindolizine (19x): mp 63-64 °C (hexane); 68% yield. Anal. (C23H25NO2‚0.1H2O) C, H, N.

8-(Benzyloxy)-3-(cycloheptylcarbonyl)-2-ethylindolizine (19xi): mp 85-86 °C (hexane); 74% yield. Anal. (C25H29NO2) C, H, N. 8-(Benzyloxy)-2-ethyl-3-(2-oxopentyl)indolizine (19xii): mp 84 °C (hexane:EtOAc); 89% yield. Anal. (C22H25NO2) C, H, N. 8-(Benzyloxy)-2-ethyl-3-(1-oxo-2-propylpentyl)indolizine (19xiii): mp 137-138 °C (hexane:EtOAc); 25% yield. 8-(Benzyloxy)-2-ethyl-3-(naphth-2-ylcarbonyl)indolizine (19xiv): amorphous solid; 70% yield. Anal. (C28H23NO2) C, H, N. 8-(Benzyloxy)-3-(3,5-di-tert-butylbenzoyl)-2-ethylindolizine (19xv): mp 131 °C (hexane:EtOAc); 82% yield. Anal. (C32H37NO2) C, H, N. 8-(Benzyloxy)-2-ethyl-3-(1-oxo-2-phenylethyl)indolizine (19xvi): mp 139-140 °C (hexane:EtOAc); 58% yield. Anal. (C25H23NO2) C, H, N. 3-(o-Benzylbenzoyl)-8-(benzyloxy)-2-ethylindolizine (19xvii): yellow oil; 58% yield. Anal. (C31H27NO2‚0.5H2O) C, H, N. 8-(Benzyloxy)-2-ethyl-3-thien-2-ylindolizine (19xviii): mp 141-142 °C (hexane:EtOAc); 82% yield. Anal. (C22H19NO2S) C, H, N, S. 8-(Benzyloxy)-2-ethyl-3-(3-thien-2-ylthien-2-yl)indolizine (19xix). 3-(Thiophene-2-yl)thiophene-2-carboxylic acid was prepared by hydrolysis of the methyl ester:21 mp 137138 °C (hexane:EtOAc); 1H NMR (CDCl3) δ 7.10 (1H, dd, J ) 3.6, 5.0 Hz), 7.26 (1H, d, J ) 5.0 Hz), 7.39 (1H, dd, J ) 1.0, 5.0 Hz), 7.55-7.60 (2H, m); IR νmax (KBr) 2845, 2606, 1671, 1273, 1245 cm-1; The acid chloride was treated as above, but the product could not be purified and used in the next preparation without further purification. 8-(Benzyloxy)-2-ethyl-3-(m-methoxybenzoyl)indolizine (19xx): mp 64-67 °C; 77% yield. Anal. (C25H23NO3) C, H, N. 8-(Benzyloxy)-2-ethyl-3-(1-oxo-2-(4-n-pentylcyclohexyl)ethyl)indolizine (19xxii): mp 64-65 °C (hexane); 41% yield. Anal. (C29H37NO2) C, H, N. 8-(Benzyloxy)-2-methy-3-(o-phenylbenzoyl)indolizine (19xxiv): mp 114-116 °C; 66.9% yield. 8-(Benzyloxy)-3-benzoyl-2-cyclopropylindolizine (19xxv): mp 144-146 °C; 81.4% yield. Anal. (C25H21NO2‚0.1H2O) C, H, N. 3-(p-n-Butylbenzoyl)-2-ethyl-8-methoxyindolizine (19xxvi): mp 90-91 °C (hexane); 72.8% yield. Anal. (C22H25NO2) C, H, N. 8-(Benzyloxy)-2-methyl-3-(1-oxo-2-cyclohexylethyl)lindolizine (19xxvii): mp 105-106 °C (hexane:EtOAc); 61% yield. Anal. (C23H25NO2) C, H, N. 8-(Benzyloxy)-3-(cyclopentylcarbonyl)-2-methylindolizine (19xxix): mp 93.5-94.5 °C; 24% yield. Anal. (C22H23NO2) C, H, N. 8-(Benzyloxy)-2-ethyl-3-(p-phenylbenzyl)indolizine (20viii): quantitative yield; 1H NMR (CDCl3) δ 1.26 (3H, t, J ) 7.2 Hz), 2.74 (2H, q, J ) 7.8 Hz), 4.28 (2H, s), 5.18 (2H, s), 6.02 (1H, d, J ) 7.2 Hz), 6.28 (1H, t, J ) 7.2 Hz), 7.11 (1H, d, J ) 8.4 Hz), 7.23-7.71 (14H, m). 8-(Benzyloxy)-3-(cyclopentylmethyl)-2-ethylindolizine (20x): 1H NMR (CDCl3) δ 1.15-1.34 (5H, m), 1.41-1.74 (6H, m), 2.18 (1H, quint, J ) 7.8 Hz), 2.65 (2H, q, J ) 7.4 Hz), 2.82 (2H, d, J ) 7.2 Hz), 5.17 (2H, s), 5.98 (1H, d, J ) 7.0 Hz), 6.34 (1H, dd, J ) 7.0, 7.4 Hz), 6.53 (1H, s), 7.3-7.5 (6H, m). 8-(Benzyloxy)-2-ethyl-3-pentylindolizine (20xii): IR νmax (KBr) 2950, 2920, 1550, 1520, 1365, 1250 cm-1; 1H NMR (CDCl3) δ 0.90 (3H, br s), 1.20-1.66 (9H, m), 2.61 (2H, q, J ) 7.4 Hz), 2.84 (2H, t, J ) 7.8 Hz), 5.16 (2H, s), 6.06 (1H, d, J ) 7.2 Hz), 6.38 (2H, m), 7.3-7.5 (6H, m). 8-(Benzyloxy)-2-ethyl-3-(2-propylpentyl)indolizine (20xiii): 25% yield; 1H NMR (CDCl3) δ 0.82-0.88 (6H, m), 1.16-1.49 (12H, m), 1.64-1.86 (1H, m), 2.57-2.74 (4H, m), 5.16 (2H, s), 5.98 (1H, d, J ) 7.4 Hz), 6.34 (1H, dd, J ) 7.2, 7.4 Hz), 6.53 (1H, s), 7.31-7.50 (6H, m). 8-(Benzyloxy)-2-ethyl-3-(naphth-2-ylmethyl)indolizine (20xiv): 1H NMR (CDCl3) δ 1.31 (3H, t, J ) 7.4 Hz), 2.76

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(2H, q, J ) 7.4 Hz), 4.39 (2H, s), 5.17 (2H, s), 6.00 (1H, d, J ) 7.4 Hz), 6.22 (1H, dd, J ) 7.0, 7.4 Hz), 6.64 (1H, s), 7.22-7.8 (13H, m). 8-(Benzyloxy)-3-(o-benzylbenzyl)-2-ethylindolizine (20xvii): 91% yield; IR νmax (neat) 2922, 1523, 1371, 1312 cm-1; 1H NMR (CDCl ) δ 1.19 (3H, t, J ) 7.4 Hz), 2.54 (2H, q, J ) 3 7.4 Hz), 4.07 (2H, s), 4.18 (2H, s), 5.16 (2H, s), 5.97 (1H, d, J ) 7.4 Hz), 6.13 (1H, dd, J ) 6.6, 7.4 Hz), 6.48 (1H, d, J ) 7.8 Hz), 6.58 (1H, s), 6.69 (1H, d, J ) 6.8 Hz) 6.98-7.51 (13H, m). 8-(Benzyloxy)-2-ethyl-3-((3-thiophene-2-ylthiophen-2yl)methyl)indolizine (20xix): 1H NMR (CDCl3) δ 1.22 (3H, t, J ) 7.4 Hz), 2.63 (2H, q, J ) 7.4 Hz), 4.41 (2H, s), 5.06 (2H, s), 5.92 (1H, d, J ) 7.0 Hz), 6.17 (1H, dd, J ) 7.0, 7.2 Hz), 6.51 (1H, s), 6.91-7.42 (11H, m). 8-(Benzyloxy)-2-ethyl-3-(m-methoxybenzyl)indolizine (20xx): quantitative yield; 1H NMR (CDCl3) δ 1.29 (3H, t, J ) 7.5 Hz), 2.72 (2H, q, J ) 7.5 Hz), 3.72 (3H, s), 4.21 (2H, s), 5.17 (2H, s), 6.01 (1H, d, J ) 7.2 Hz), 6.26 (1H, t, J ) 7.2 Hz), 6.58-6.75 (4H, m), 7.11-7.44 (5H, m), 7.46-7.63 (2H, m). 8-(Benzyloxy)-2-ethyl-3-(4-n-pentylcyclohexyl)methylindolizine (20xxii): 1H NMR (CDCl3) δ 0.70-1.80 (24H, m), 2.57-2.71 (4H, m), 5.17 (2H, s), 5.98 (1H, d, J ) 7.4 Hz), 6.34 (1H, dd, J ) 7.0, 7.4 Hz), 6.53 (1H, s), 7.26-7.51 (6H, m). 8-(Benzyloxy)-3-(biphenyl-2-ylmethyl)-2-methylindolizine (20xxiv): mp 98-99 °C; quantitative yield; 1H NMR (CDCl3) δ 2.26 (3H, s), 4.11 (2H, s), 5.15 (2H, s), 5.97 (1H, d, J ) 6.9 Hz), 6.19 (1H, t, J ) 7.1 Hz), 6.52 (1H, s), 6.72 (1H, d, J ) 6.9 Hz), 6.93 (1H, d, J ) 6.9 Hz), 7.10-7.16 (1H, m), 7.237.54 (12H, m). 3-Benzyl-8-(benzyloxy)-2-cyclopropylindolizine (20xxv): 94% yield; 1H NMR (CDCl3) δ 0.67-0.75 (2H, m), 0.87-0.97 (2H, m), 1.86-2.00 (1H, m), 4.34 (2H, s), 5.14 (2H, s), 5.98 (1H, d, J ) 7.4 Hz), 6.21-6.31 (1H + 1H, m), 7.09-7.49 (11H, m). 3-(p-n-Butylbenzyl)-2-ethyl-8-methoxyindolizine (20xxvi): oil; 67.9% yield; 1H NMR (CDCl3) δ 0.90 (3H, t, J ) 7.3 Hz), 1.28 (3H, t, J ) 7.5 Hz), 1.32 (2H, m), 1.55 (2H, m), 2.54 (2H, t, J ) 7.6 Hz), 2.71 (2H, m), 3.92 (3H, s), 4.19 (2H, s), 5.90 (1H, d, J ) 7.2 Hz), 6.28 (1H, t, J ) 7.1 Hz), 6.94 (1H, d, J ) 8.2 Hz), 7.04 (1H, d, J ) 8.0 Hz), 7.23 (1H, d, J ) 7.0 Hz). 8-(Benzyloxy)-2-ethyl-3-(cyclohexylmethyl)indolizine (20xxvii): 1H NMR (CDCl3) δ 1.00-1.26 (5H, m), 1.552.25 (6H, m), 2.25 (3H, s), 2.68 (2H, d, J ) 6.9 Hz), 5.16 (2H, s), 5.98 (1H, d, J ) 7.2 Hz), 6.34 (1H, dd, J ) 6.9, 7.2 Hz), 6.47 (1H, s), 7.30-7.49 (6H, m). 2-(8-(Benzyloxy)-2-ethyl-3-(substituted methyl)indolizin-1-yl)glyoxylamide (25). These compounds were prepared from 20, according to the procedure described for the synthesis of 5a from 4. 2-(3-Benzyl-8-(benzyloxy)-2-ethylindolizin-1-yl)glyoxylamide (25i): mp 188-189 °C; 63% yield; IR νmax (Nujol) 3425, 3203, 2968, 2929, 1693, 1621, 1313 cm-1; 1H NMR (CDCl3) δ 1.22 (3H, t, J ) 7.4 Hz), 2.85 (2H, q, J ) 7.4 Hz), 4.24 (3H, s), 4.78 (1H, br s), 5.13 (1H, s), 6.16 (1H, br s), 6.38 (1H, d, J ) 7.0 Hz), 6.49 (1H, dd, J ) 6.6, 7.4, Hz), 7.04-7.14 (2H, m), 7.20-7.49 (9H, m). Anal. (C26H24N2O3‚0.2H2O) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-(o-phenylbenzyl)indolizin1-yl)glyoxylamide (25ii): mp 183-185 °C (ether:hexane); 79.0% yield. Anal. (C32H28N2O3) C, H, N. 2-(8-(Benzyloxy)-3-(m-chlorobenzyl)-2-ethylindolizin1-yl)glyoxylamide (25iii). mp 145-148 °C (ether:hexane); 80% yield; LSIMS m/z 446 [M]+•, 447 [M + H]+, 893 [2M + H]+. (8-(Benzyloxy)-2-ethyl-3-(m-(trifluoromethyl)benzyl)indolizin-1-yl)glyoxylamide (25iv): mp 182-185 °C (CH2Cl2:hexane); 76% yield. (8-(Benzyloxy)-2-ethyl-3-(1-naphthylmethyl)indolizin1-yl)glyoxylamide (25v): mp 189-190 °C (benzene); 76.0% yield. Anal. (C30H26N2O3) C, H, N. (8-(Benzyloxy)-2-cyclopropyl-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (25vi): mp 185-186 °C (CH2Cl2: hexane); quantitative yield. Anal. (C33H28N2O3 0.3H2O) C, H, N.

2-(3-Benzyl-8-(benzyloxy)-2-methylindolizin-1-yl)glyoxylamide (25vii): mp 212-214 °C; 96.2% yield. Anal. (C25H22N2O3) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-(p-phenylbenzyl)indolizine1-yl)glyoxylamide (25viii): mp 196-199 °C; 61% yield. Anal. (C32H28N2O3‚0.2H2O) C, H, N. 2-(8-(Benzyloxy)-3-(cyclohexylmethyl)-2-ethylindolizin1-yl)glyoxylamide (25ix): mp 176 °C (hexane:EtOAc); 85% yield. Anal. (C26H30N2O3) C, H, N. 2-(8-(Benzyloxy)-3-(cyclopentylmethyl)-2-ethylindolizin1-yl)glyoxylamide (25x): mp 161-162 °C (hexane:AcOEt); 77% yield. Anal. (C25H28N2O3) C, H, N. 2-(8-(Benzyloxy)-3-(cycloheptylmethyl)-2-ethylindolizin1-yl)glyoxylamide (25xi): mp 144-145 °C (hexane); 76% yield. Anal. (C27H32N2O3) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-(oxopentyl)indolizin-1-yl)glyoxylamide (25xii): mp 141-142 °C (hexane:EtOAc); 77% yield. Anal. (C24H28N2O3) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-(2-propylpentyl)indolizin-1yl)glyoxylamide (25xiii): mp 159-160 °C (hexane:EtOAc); 82% yield. Anal. (C27H34N2O3‚1.6H2O) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-(naphth-2-ylmethyl)indolizin1-yl)glyoxylamide (25xiv): mp 209-210 °C (EtOAc); 77% yield. Anal. (C30H26N2O3) C, H, N. 2-(8-(Benzyloxy)-3-(3,5-di-tert-butylbenzyl)-2-ethylindolizin-1-yl)glyoxylamide (25xv): mp 230-231 °C (EtOAc); 59% yield. Anal. (C34H40N2O3‚0.2H2O) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-(2-phenylethyl)indolizin-1yl)glyoxylamide (25xvi): mp 188-189 °C (EtOAc); 79% yield. Anal. (C27H26N2O3‚0.3H2O) C, H, N. 2-(8-(Benzyloxy)-3-(o-benzylbenzyl)-2-ethylindolizin-1yl)glyoxylamide (25xvii): mp 178-179 °C (hexane:EtOAc); 93% yield. Anal. (C33H30N2O3) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-(thiophene-2-ylmethyl)indolizin-1-yl)glyoxylamide (25xviii): mp 191-192 °C (EtOAc); 73% yield. Anal. (C24H22N2O3S) C, H, N, S. 2-(8-(Benzyloxy)-2-ethyl-3-((3-thiophene-2-ylthiophene2-yl)methyl)indolizin-1-yl)glyoxylamide (25xix): mp 208209 °C (EtOAc); 10% Yield (two steps). 2-(8-(Benzyloxy)-2-ethyl-3-(m-methoxybenzyl)indolizine-1-yl)glyoxylamide (25xx): mp 180-182 °C; 61% yield. Anal. (C27H26N2O4‚0.1H2O) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-(o-nitrobenzyl)indolizine-1yl)glyoxylamide (25xxi): mp 205-208 °C; 8% yield. Anal. (C26H23N3O5) C, H, N. 2-(8-(Benzyloxy)-2-ethyl-3-((4-n-pentylcyclohexyl)methyl)indolizin-1-yl)glyoxylamide (25xxii): mp 169-170 °C (EtOAc); 80% yield. Anal. (C31H40N2O3‚0.4H2O) C, H, N. 2-(3-(Adamant-1-yl)-8-(benzyloxy)-2-ethylindolizin-1yl)glyoxylamide (25xxiii): mp 225-226 °C (EtOAc); 21% Yield (three steps). Anal. (C29H32N2O3) C, H, N. 2-(8-(Benzyloxy)-3-(biphenyl-2-ylmethyl)-2-methylindolizin-1-yl)-glyoxylamide (25xxiv): mp 198-200 °C; 82.7% yield. Anal. (C31H26N2O3‚0.2H2O) C, H, N. 2-(3-Benzyl-8-(benzyloxy)-2-cyclopropylindolizin-1-yl)glyoxylamide (25xxv): mp 206-207 °C; 30% yield. Anal. (C27H24N2O3‚0.3H2O) C, H, N. 2-(3-(p-n-Butylbenzyl)-2-ethyl-8-methoxyindolizin-1yl)glyoxylamide (25xxvi): mp 195-196 °C (benzene); 96.8% yield. Anal. (C24H28N2O3) C, H, N. 2-(8-(Benzyloxy)-3-cyclohexyl-2-methylindolizin-1-yl)glyoxylamide (25xxvii): mp 222-223 °C (EtOAc); 88% yield. Anal. (C25H18N2O3) C, H, N. 2-(8-(Benzyloxy)-3-cyclopentylmethyl-2-cyclopropylindolizin-1-yl)glyoxylamide (25xxviii). Compounds 19xxviii and 20xxviii were prepared by the above procedure and used in the next preparation without further purification: mp 186187 °C; 28% yield. Anal. (C26H28N2O3) C, H, N. 2-(8-(Benzyloxy)-3-(cyclopentylmethyl)-2-methylindolizin-1-yl)glyoxylamide (25xxix): Compound 20xxix was prepared by the general procedure 2 cited above and used in the next preparation without further purification: mp 174175 °C; 66% yield. Anal. (C24H26N2O3) C, H, N. 2-(3-(Substituted methyl)-8-hydroxy-2-ethylindolizin1-yl)glyoxylamide (26). General procedure 1: These com-



pounds were prepared from 25, according to the procedure described for the synthesis of 12 from 13. General procedure 2: A 1 M solution of BBr3 in CH2Cl2 (3.3 molar equiv) was added to a solution of 25 in CH2Cl2. The mixture was stirred for 3 h to 1 d. Ice water was added. The organic phase was washed with water and dried. After removal of the solvent, the residue was purified by recrystallization or column chromatography. 2-(3-Benzyl-2-ethyl-8-hydroxyindolizin-1-yl)glyoxylamide (26i): mp 194-195 °C (AcOEt); IR νmax (KBr) 3469, 3308, 2969, 1688, 1567, 1317 cm-1; 1H NMR (CDCl3:CD3OD) δ 1.23 (3H, t, J ) 7.8 Hz), 2.90 (2H, q, J ) 7.8 Hz), 4.22 (2H, s), 6.71 (1H, d, J ) 7.4 Hz), 6.78 (1H, dd, J ) 6.6, 7.4 Hz), 7.02-7.09 (2H, m), 7.18-7.33 (4H, m). Anal. (C19H18N2O3 0.1H2O) C, H, N. 2-(2-Ethyl-8-hydroxy-3-(o-phenylbenzyl)indolizin-1yl)glyoxylamide (26ii): mp 195-196 °C (dec) (ether:hexane); 95.0% yield. Anal. (C25H22N2O3‚0.1H2O) C, H, N. 2-(3-(m-Chlorobenzyl)-2-ethyl-8-hydroxyindolizin-1yl)glyoxylamide (26iii): mp 144-146 °C (AcOEt:hexane); 88% yield; LSIMS m/z 356 [M]+•, 357 [M + H]+, 713 [2M + H]+. 2-(2-Ethyl-8-hydroxy-3-(m-(trifluoromethyl)benzyl)indolizin-1-yl)glyoxylamide (26iv): mp 142-146 °C (AcOEt: hexane); 96% yield. 2-(2-Ethyl-8-hydroxy-3-(1-naphthylmethyl)indolizin-1yl)glyoxylamide (26v): mp 176-178 °C (benzene); 84.5% yield. Anal. (C23H20N2O3‚0.5C6H6) C, H, N. 2-(2-Cyclopropyl-8-hydroxy-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (26vi): mp 189-191 °C (AcOEt: hexane); 95% yield. Anal. (C26H22N2O3‚0.2H2O) C, H, N. 2-(3-Benzyl-8-hydroxy-2-methylindolizin-1-yl)glyoxylamide (26vii): mp 189-192 °C; 94.9% yield. Anal. (C18H16N2O3) C, H, N. 2-(2-Ethyl-8-hydroxy-3-(o-phenylbenzyl)indolizine-1yl)glyoxylamide (26viii): quantitative yield; 1H NMR (CDCl3) δ 1.25 (3H, t, J ) 7.5 Hz), 2.93 (2H, q, J ) 7.5 Hz), 4.25 (2H, s), 5.76 (1H, br s), 6.39 (1H, br s), 6.70 (1H, d, J ) 7.2 Hz), 6.79 (1H, t, J ) 7.1 Hz), 7.08-7.78 (10H, m), 12.90 (1H, s). 2-(3-(Cyclopentylmethyl)-2-ethyl-8-hydroxyindolizin1-yl)glyoxylamide (26x): 1H NMR (CDCl3) δ 1.1-1.3 (6H, m), 1.46-1.76 (5H, m), 2.06-2.24 (1H, m), 2.78-2.91 (4H, m), 5.70 (1H, br s), 6.3 (1H, br s), 6.72 (1H, d, J ) 7.8 Hz), 6.91 (1H, dd, J ) 6.8, 7.8 Hz), 7.54 (1H, d, J ) 6.8 Hz), 12.93 (1H, s). 2-(3-(Cycloheptylmethyl)-2-ethyl-8-hydroxyindolizin1-yl)glyoxylamide (26xi): 1H NMR (CDCl3) δ 1.13-1.9 (16H, m), 2.67 (2H, d, J ) 7.4 Hz), 2.83 (2H, q, J ) 7.8 Hz), 5.70 (1H, br s), 6.30 (1H, br s), 6.72 (1H, d, J ) 7.5 Hz), 6.92 (1H, dd, J ) 6.2, 7.8 Hz), 7.48 (1H, d, J ) 6.2 Hz), 12.94 (1H, s). 2-(2-Ethyl-8-hydroxy-3-oxopentylindolizin-1-yl)glyoxylamide (26xii). Anal. (C17H22N2O3) C, H, N. 2-(2,5-Di-tert-butylbenzyl)-8-hydroxy-2-ethylindolizin1-yl)glyoxylamide (26xv): 1H NMR (CDCl3) δ 1.18-1.80 (21H, m), 2.91 (2H, q, J ) 7.4 Hz), 4.20 (2H, s), 5.71 (1H, br s), 6.31 (1H, br s), 6.70-6.88 (4H, m), 7.26-7.33 (2H, m), 12.90 (1H, s). 2-(2-Ethyl-8-hydroxy-3-thien-2-ylindolizin-1-yl)glyoxylamide (26xviii): mp 163-164 °C (hexane:EtOAc); 40% yield; MS m/z 328 [M]+. 2-(2-Ethyl-8-hydroxy-3-((3-thien-2-ylthien-2-yl)methyl)indolizin-1-yl)glyoxylamide (26xix): 1H NMR (CDCl3:CD3OD) δ 1.28 (3H, t, J ) 7.4 Hz), 2.91 (2H, q, J ) 7.4 Hz), 4.50 (2H, s), 6.72 (1H, d, J ) 7.8 Hz), 6.80 (1H, dd, J ) 6.2, 7.8 Hz), 7.10-7.43 (6H, m). 2-(2-Ethyl-8-hydroxy-3-(m-methoxybenzyl)indolizin-1yl)glyoxylamide (26xx): mp 140-143 °C; 86% yield. 2-(2-Ethyl-8-hydroxy-3-(o-nitrobenzyl)indolizin-1-yl)glyoxylamide (26xxi): mp 174-178 °C (dec); 85% yield. Anal. (C19H17N3O5) C, H, N. 8-Hydroxy-2-ethyl-3-(4-n-pentylcyclohexyl)indolizin1-yl)glyoxylamide (26xxii): mp 99-100 °C (hexane:EtOAc). Anal. (C24H34N2O3) C, H, N. 2-(3-(Biphenyl-2-ylmethyl)-8-hydroxy-2-methylindolizin1-yl)glyoxylamide (26xxiv): mp 129-130 °C; 77.6% yield. Anal. (C24H20N2O3‚0.2H2O) C, H, N.

2-(3-Benzyl-2-cyclopropyl-8-hydroxyindolizin-1-yl)glyoxylamide (26xxv): mp 188-190 °C; 96.7% yield. Anal. (C20H18N2O3‚0.5AcOEt) C, H, N. 2-(3-(p-n-Butylbenzyl)-2-ethyl-8-hydroxyindolizin-1yl)glyoxylamide (26xxvi): mp 145-148 °C (benzene); 59.3% yield. Anal. (C23H26N2O3‚0.1H2O) C, H, N. 2-(3-(Cyclohexylmethyl)-8-hydroxy-2-methylindolizin1-yl)glyoxylamide (26xxvii): 1H NMR (CDCl3) δ 1.00-1.80 (11H, m), 2.33 (3H, s), 2.65 (2H, d, J ) 6.9 Hz), 5.7 (1H, br s), 6.24 (1H, br s), 6.71 (1H, d, J ) 7.8 Hz), 6.91 (1H, dd, J ) 6.3, 7.8 Hz), 7.46 (1H, d, J ) 6.3 Hz), 12.97 (1H, s). 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(substituted methyl)indolizin-1-yl)glyoxylamide (27). General procedure: Compound 26 (1 mmol), methyl bromoacetate (1.1 mmol), K2CO3 (3 mmol), KI (0.2 mmol), and DMF (3 mL) were stirred for 5 h. Water was added. The mixture was extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvent, the residue was purified by recrystallization or column chromatography. (8-((Carboxymethyl)oxy)indolizin-1-yl)glyoxylamide (28). General procedure: Aqueous KOH (1 N, 4 mL) was added to a solution of the ester 27 (2 mmol) in MeOH (21 mL). The solution was stirred at room temperature for 40 min, washed with ether, acidified with 2 N HCl, and extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvent, the residue was recrystallized. (3-Benzyl-8-((carbethoxymethyl)oxy)-2-ethylindolizin1-yl)glyoxylamide (27i) and carboxylic acid 28i: mp 191192 °C (AcOEt:hexane); 23% yield; IR νmax (KBr) 3409, 3161, 2968, 1727, 1686, 1630, 1319, 1092 cm-1; 1H NMR (CDCl3) δ 1.20-1.32 (6H, m), 2.88 (2H, q, J ) 7.4 Hz), 4.18-4.29 (4H, m), 4.72 (2H, s), 6.12 (1H, br s), 6.25 (1H, d, J ) 7.4 Hz), 6.49 (1H, dd, J ) 7.0, 7.4 Hz), 6.69 (1H, br s), 7.07-7.11 (2H, m), 7.20-7.35 (4H, m). Anal. (C23H24N2O5 0.8H2O) C, H, N. 28i: mp 244-245 °C (AcOEt:ether); 42% yield; IR νmax (KBr) 3855, 2974, 2931, 1703, 1660, 1625, 1312, 1092 cm-1; 1H NMR (CDCl3:CD3OD) δ 1.22 (3H, t, J ) 7.4 Hz), 2.90 (2H, q, J ) 7.4 Hz), 4.27 (2H, s), 4.73 (2H, s), 6.37 (1H, d, J ) 7.8 Hz), 6.73 (1H, dd, J ) 6.6, 7.8 Hz), 7.06-7.43 (6H, m); EIMS m/z 380 [M+]. Anal. (C21H20N2O5 0.7H2O) C, H, N. (8-((Carbethoxymethyl)oxy)-2-ethyl-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (27ii) and carboxylic acid 28ii: mp 127-129 °C (ether:hexane); 86.0% yield. Anal. (C29H28N2O5) C, H, N. 28ii: mp 209-212 °C (dec) (ether:hexane); 93% yield. Anal. (C27H24N2O5‚0.3H2O) C, H, N. (8-((Carbethoxymethyl)oxy)-3-(m-chlorobenzyl)-2-ethylindolizin-1-yl)glyoxylamide (27iii): mp 172-175 °C (AcOEt:hexane); 73% yield; LSIMS m/z 442 [M]+•, 443 [M + H]+, 885 [2M + H]+. 28iii: mp 230-233 °C (dec) (ether:hexane); 79% yield; LSIMS m/z 414 [M]+•, 415 [M + H]+, 829 [2M + H]+. (8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(m-(trifluoromethyl)benzyl)indolizin-1-yl)glyoxylamide (27iv) and carboxylic acid 28iv: mp 136-137 °C (AcOEt:hexane); 59% yield. Anal. (C23H21N2O5F3‚0.2H2O) C, H, N, F. 28iv: mp 235-237 °C (dec) (CH2Cl2:hexane); 97% yield. (8-Carbethoxymethyloxy-2-ethyl-3-(1-naphthylmethyl)indolizin-1-yl)glyoxylamide (27v) and carboxylic acid 28v: 37.8% yield. 28v: 68.4% yield. (8-((Carbomethoxymethyl)oxy)-2-cyclopropyl-3-(ophenylbenzyl)indolizin-1-yl)glyoxylamide (27vi) and carboxylic acid 28vi: mp 178-179 °C (AcOEt:hexane); 69% yield. Anal. (C29H26N2O5‚0.2H2O) C, H, N. 28vi: mp 205-207 °C (dec) (AcOEt:hexane); 93% yield. Anal. (C28H24N2O5‚0.3H2O) C, H, N. (3-Benzyl-8-((carbethoxymethyl)oxy)-2-methylindolizin1-yl)glyoxylamide (27vii) and carboxylic acid 28vii: mp 193-195 °C; 41.4% yield. Anal. (C22H22N2O5) C, H, N. 28vii: mp 245-246 °C (dec); 86.7% yield. Anal. (C20H18N2O5 0.2H2O) C, H, N. 2-(2-Ethyl-8-((carbomethoxymethyl)oxy)-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (27viii) and carboxylic acid 28viii: mp 221-222 °C, 54% yield. Anal. (C28H26N2O5) C, H, N.

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28viii: mp 229-234 °C (dec); 84% yield. Anal. (C27H24N2O5‚0.1H2O) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-3-(cyclohexylmethyl)2-ethylindolizin-1-yl)glyoxylamide (27ix) and carboxylic acid 28ix: mp 149-150 °C, (hexane:EtOAc); 19% yield from 25ix. Anal. (C22H28N2O5) C, H, N. 28ix: mp 224-225 °C (AcOEt); MS m/z 386 [M]+. 2-(8-((Carbomethoxymethyl)oxy)-3-(cyclopentylmethyl)2-ethylindolizin-1-yl)glyoxylamide (27x) and carboxylic acid 28x: mp 158-159 °C (AcOEt); quantitative yield. Anal. (C21H26N2O5) C, H, N. 28x: 43% yield. Anal. (C20H24N2O5‚0.4H2O) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-3-(cycloheptylmethyl)2-ethylindolizin-1-yl)glyoxylamide (27xi) and carboxylic acid 28xi: mp 147-148 °C (AcOEt); 79% yield. Anal. (C23H30N2O5) C, H, N. 28xi: 76% yield. Anal. (C22H28N2O5) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(oxopentyl)indolizin-1-yl)glyoxylamide (27xii) and carboxylic acid 28xii: mp 140-141 °C (hexane:EtOAc); 36% yield. Anal. (C20H26N2O5‚0.5H2O) C, H, N. 28xii: mp 232-233 °C (acetone:AcOEt); 37% yield; MS m/z 360 [M]+. 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(2-propylpentyl)indolizin-1-yl)glyoxylamide (27xiii) and carboxylic acid 28xiii: mp 114-115 °C (hexane:EtOAc); 84% yield. Anal. (C23H32N2O5) C, H, N. 28xiii: mp 176-177 °C (hexane:AcOEt); 81% yield; MS m/z 402 [M]+. Anal. (C22H30N2O5‚1.1H2O) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(naphth-2ylmethyl)indolizin-1-yl)glyoxylamide (27xiv) and carboxylic acid 28xiv: mp 195-196 °C (EtOAc); quantitative yield. Anal. (C26H24N2O5‚0.3H2O) C, H, N. 28xiv: mp 236-237 °C (AcOEt); 33% yield. Anal. (C25H22N2O5‚0.6H2O) C, H, N. 2-(8-((Carboxymethyl)oxy)-3-(3,5-di-tert-butyl)benzyl)2-ethylindolizin-1-yl)glyoxylamide (27xv) and carboxylic acid 28xv: mp 186-187 °C (EtOAc); 83% Yield (two steps). Anal. (C30H38N2O5‚0.2H2O) C, H, N. 28xv: mp 144-145 °C (hexane:EtOAc); 43% yield; MS m/z 492 [M]+. Anal. (C29H26N2O5‚1.7H2O) C, H, N. 2-(8-((Carbomethoxymethyl)oxy-2-ethyl-3-(2-phenylethyl)indolizin-1-yl)glyoxylamide (27xvi) and carboxylic acid 28xvi: mp 175-176 °C (EtOAc); 47% Yield (two steps). Anal. (C23H24N2O5‚0.1H2O) C, H, N. 28xvi: mp 233-234 °C (EtOAc); 48% yield. Anal. (C22H22N2O5) C, H, N. 2-(3-o-Benzylbenzyl)-8-((carbomethoxymethyl)oxy)-2ethylindolizin-1-yl)glyoxylamide (27xvii) and carboxylic acid 28xvii: mp 190-191 °C (EtOAc); 65% Yield (two steps). Anal. (C29H28N2O5‚0.5H2O) C, H, N. 28xvii: mp 220-221 °C (EtOAc); 42% yield. Anal. (C28H26N2O5) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-thien-2-ylindolizin-1-yl)glyoxylamide (27xviii) and carboxylic acid 28xviii: mp 182 °C (hexane:EtOAc); 75% yield. Anal. (C20H20N2O5 S‚0.2H2O) C, H, N, S. 28xviii: mp 251-252 °C (EtOAc); 32% yield. Anal. (C19H18N2O5S‚0.6H2O) C, H, N, S. 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-((3-thien-2ylthien-2-yl)methyl)indolizin-1-yl)glyoxylamide (27xix) and carboxylic acid 28xix: mp 176-177 °C. Anal. (C24H22N2O5 S2‚0.2H2O) C, H, N, S. 28xix: mp 209-210 °C; 54.5% yield. Anal. (C23H20N2O5S2) C, H, N, S. 2-(2-Ethyl-8-((carbomethoxymethyl)oxy)-3-(m-methoxybenzyl)indolizin-1-yl)glyoxylamide (27xx) and carboxylic acid 28xx: mp 155-157 °C; 85% yield. Anal. (C23H24N2O6) C, H, N. 28xx: mp 219-221 °C (dec); 80% yield. Anal. (C22H22N2O6‚0.8H2O) C, H, N. 2-(2-Ethyl-8-((carbomethoxymethyl)oxy)-3-(o-nitrobenzyl)indolizin-1-yl)glyoxylamide (27xxi) and carboxylic acid 28xxi: mp 156-157 °C; 96% yield. 28xxi: mp 208-210 °C (dec); 69% yield. Anal. (C21H19N3O7‚0.3H2O) C, H, N.

2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-((4-n-pentylcyclohexyl)methyl)indolizin-1-yl)glyoxylamide (27xxii) and carboxylic acid 28xxi: mp 175-176 °C (hexane:EtOAc), 92% yield (two steps). Anal. (C27H38N2O5) C, H, N. 28xxii: mp 224-225 °C (EtOAc); 59% yield (from Na salt). Anal. (C26H36N2O5‚0.7H2O) C, H, N. 2-(3-(Adamant-1-yl-8-((carbomethoxymethyl)oxy)-2methylindolizin-1-yl)glyoxylamide (27xxiii) and carboxylic acid 28xxiii: mp 191-192 °C (EtOAc); 38% yield (two steps); MS m/z 438 [M]+. 28xxiii: mp 237-238 °C (EtOAc); 60% yield; MS m/z 424 [M]+. 2-(3-Benzyl-8-(carbomethoxymethyl)oxy-2-cyclopropylindolizin-1-yl)-glyoxylamide (27xxv) and carboxylic acid 28xxv: mp 186-188 °C; 74.5% yield; IR νmax (CHCl3) 3502, 3390, 1759, 1737, 1697, 1642 cm-1. Anal. (C23H22N2O5‚0.1H2O) C, H, N. 28xxv: mp 235-237 °C; 74.6% yield. Anal. (C22H20N2O5‚ 0.2H2O) C, H, N. 2-(3-(p-n-Butylbenzyl)-8-((carbomethoxymethyl)oxy)2-ethylindolizin-1-yl)glyoxylamide (27xxvi) and carboxylic acid 28xxvi: mp 174-176 °C (EtOAc:benzene); 70.9% yield. Anal. (C23H26N2O3‚0.1H2O) C, H, N. 28xxvi: mp 217-220 °C (EtOAc); 92.4% yield. Anal. (C23H26N2O3‚0.1H2O) C, H, N. 2-(8-(Carbomethoxymethyoxy-3-(cyclohexylmethyl)-2methylindolizin-1-yl)glyoxylamide (27xxvii) and carboxylic acid 28xxvii: mp 177-178 °C (hexane:EtOAc); 68% yield (two steps). Anal. (C21H26N2O5‚0.6H2O) C, H, N. 28xxvii: mp 235-236 °C (hexane:EtOAc). Anal. (C20H24N2O5‚0.8H2O) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-3-(cyclopentylmethyl)2-cyclopropylindolizin-1-yl)glyoxylamide (27xxviii) and carboxylic acid 28xxviii. Compound 26xxviii was prepared as cited above and used in the next preparation without further purification: mp 175-176 °C, 70.4% yield. Anal. (C22H26N2O5) C, H, N. 28xxviii: mp 237-238 °C, 20% yield. Anal. (C21H24N2O5) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-3-(cyclopentylmethyl)2-methylindolizin-1-yl)glyoxylamide (27xxix) and carboxylic acid 28xxix: mp 149-150 °C, 63% yield. Anal. (C20H24N2O5) C, H, N. 28xxix: mp 249-251 °C (dec), 85% yield. Anal. (C19H22N2O5) C, H, N. 3-((Carbomethoxymethyl)oxy)-2-methylpyridine (29). This compound was prepared from 3-hydroxy-2-methylpyridine by the procedure cited for the preparation of 14 from 13. The residue was chromatographed (25 g) in EtOAc:hexane (2:1) to give an oil (791 mg, 60.1%): 1H NMR (CDCl3) δ 2.55 (3H, s), 3.81 (3H, s), 4.67 (2H, s), 6.97 (1H, dd, J ) 8.2 Hz), 7.09 (1H, dd, J ) 8.2, 4.8 Hz), 8.14 (1H, dd, J ) 1.4, 4.6 Hz). 8-(Carbomethoxymethyl)oxy)-2-methylindolizine (30a). ((2-Methylpyridin-3-yl)oxy)acetic acid methyl ester (29) (1.75 g, 9.66 mmol) and chloroacetone (0.77 mL, 9.66 mmol) were heated at 95 °C under N2 for 2 h. DBU (3.2 mL, 21.3 mmol) in benzene (11 mL) was added to the salt. The mixture was then refluxed under N2 for 1 h, poured into ice water, and then extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvents at reduced pressure, the residue was recrystallized from ether:hexane to give 804 mg (40% yield) of the title compound: mp 59-62 °C; 1H NMR (CDCl3) δ 2.30 (3H, s), 3.80 (3H, s), 4.72 (2H, s), 5.82 (1H, d, J ) 7.5 Hz), 6.26 (1H, t, J ) 6.9 Hz), 6.46 (1H, s), 7.08 (1H, s), 7.51 (1H, d, J ) 6.6 Hz). 8-((Carbomethoxymethyl)oxy)-2-ethylindolizine (30b): oil; 601 mg (82.6% from 53); 1H NMR (CDCl3) δ 1.29 (3H, t, J ) 7.5 Hz), 2.70 (2H, q, J ) 7.8 Hz), 3.81 (3H, s), 4.74 (2H, s), 5.86 (1H, d, J ) 6.9 Hz), 6.30 (1H, t, J ) 7.1 Hz), 6.51 (1H, s), 7.11 (1H, s), 7.56 (1H, d, J ) 4.2 Hz). ((2-Isopropylindolizin-8-yl)oxy)acetic acid methyl ester (30c): oil, 59% yield; 1H NMR (CDCl3) δ 1.30 (6H, d, J ) 6.6 Hz), 3.02 (1H, sept, J ) 6.6 Hz), 3.81 (3H, s), 4.73 (2H, s), 5.82 (1H, d, J ) 7.4 Hz), 6.27 (1H, t, J ) 7.0 Hz), 6.53 (1H, s), 7.12 (1H, s), 7.53 (1H, d, J ) 7.0 Hz).



8-((Carbomethoxymethyl)oxy)-2-cyclopropylindolizine (30d): oil; 76% yield; 1H NMR (CDCl3) δ 0.65 (2H, m), 0.92 (2H, m), 1.90 (1H, m), 3.81 (3H, s), 4.71 (2H, s), 5.82 (1H, d, J ) 7.4 Hz), 6.28 (1H, d, J ) 7.4 Hz), 6.28 (1H, t, J ) 7.2 Hz), 6.34 (1H, s), 7.13 (1H, d, J ) 1.4 Hz), 7.50 (1H, d, J ) 6.8 Hz). 2-tert-Butyl-8-((carbomethoxymethyl)oxy)indolizine (30e): oil; 48.0% yield; 1H NMR (CDCl3) δ 1.34 (9H, s), 3.82 (3H, s), 4.73 (2H, s), 5.82 (1H, d, J ) 7.5 Hz), 6.27 (1H, t, J ) 6.9 Hz), 6.27 (1H, t, J ) 6.9 Hz), 6.56 (1H, s), 7.13 (1H, s), 7.53 (1H, d, J ) 7.2 Hz). 8-((Carbomethoxymethyl)oxy)-2-cyclopentylindolizine (30f): oil; 14.3% yield; 1H NMR (CDCl3) δ 1.6-2.2 (8H, m), 3.11 (1H, m), 3.83 (3H, s), 4.74 (2H, s), 5.84 (1H, d, J ) 7.4 Hz), 6.29 (1H, t, J ) 7.0 Hz), 6.53 (1H, s), 7.14 (1H, s), 7.34 (1H, d, J ) 7.2 Hz). 8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(o-phenylbenzoyl)indolizine (31b). This compound was prepared from 30b, according to the procedure cited for the preparation of 20 from 19: 83% yield; 1H NMR (CDCl3) δ 1.05 (3H, t, J ) 7.5 Hz), 2.07 (2H, q, J ) 7.5 Hz), 3.82 (3H, s), 4.74 (2H, s), 6.31 (1H, d, J ) 7.4 Hz), 6.49 (1H, d, J ) 0.6 Hz), 6.65 (1H, t, J ) 7.4 Hz), 7.10-7.25 (3H, m), 7.30-7.40 (2H, m), 7.42-7.58 (5H, m), 9.40 (1H, d, J ) 7.4 Hz). 8-((Carbomethoxymethyl)oxy)-3-(cyclohexylcarbonyl)2-cyclopropylindolizine (31c): mp 110-111.5 °C; 74% yield. 2-Alkyl-8-((carbomethoxymethyl)oxy)-3-(substituted methyl)indolizine (32). General procedure: A solution of 30 (1.30 mmol) and alkyl iodide (1.56 mmol) in benzene (5 mL) was allowed to stand at room temperature for 2 d. EtOAc was added. The mixture was washed with NaHCO3 and with water, dried, and concentrated. The residue was chromatographed in hexane:benzene (1:2). 8-((Carbomethoxymethyl)oxy)-3-(cyclohexylmethyl)2-cyclopropylindolizine (32xxx): 42.8% yield; 1H NMR (CDCl3) δ 0.64-0.69 (2H, m), 0.88-0.94 (2H, m), 1.04-1.17 (5H, m), 1.62-1.74 (6H, m), 1.80-1.89 (1H, m), 2.80 (2H, d, J ) 6.6 Hz), 3.81 (3H, s), 4.72 (2H, s), 5.81 (1H, d, J ) 6.9 Hz), 6.22 (1H, s), 6.33 (1H, t, J ) 7.1 Hz), 7.40 (1H, d, J ) 7.2 Hz). 8-((Carbomethoxymethyl)oxy)-2-isopropyl-3-(ophenylbenzyl)indolizine (32xxxi): mp 115-117 °C; 37% yield. Anal. (C27H27NO3‚0.3C6H6) C, H, N. 1,3-Bis(o-phenylbenzyl)-8-((carbomethoxymethyl)oxy)2-isopropylindolizine: mp 215-219 °C (AcOEt:hexane); 9.2% yield. Anal. (C40H37NO3‚0.6H2O) C, H, N. 2-tert-Butyl-8-((carbomethoxymethyl)oxy)-3-(ophenylbenzyl)indolizine (32xxxii): mp 155-157 °C (hexane); 22.5% yield. Anal. (C28H29NO3‚0.4C6H6) C, H, N. 1,3-Bis(o-phenylbenzyl)-2-tert-butyl-8-((carbomethoxymethyl)oxy)indolizine: mp 230-234 °C; 1.8% yield; IR ν max (Nujol) 1767, 1732, 1472, 1450, 1438 cm-1; 1H NMR (CDCl3) δ 1.19 (9H, s), 3.64 (3H, s), 4.29 (2H, s), 4.44 (2H, s), 4.61 (2H, br s), 5.73 (1H, d, J ) 7.2 Hz), 6.16 (1H, t, J ) 7.2 Hz), 6.54 (1H, d, J ) 7.8 Hz), 6.81 (1H, t, J ) 7.5 Hz), 6.99 (1H, d, J ) 7.5 Hz), 7.1-7.55 (8H, m). 8-((Carbomethoxymethyl)oxy)-2-cyclopentyl-3-(ophenylbenzyl)indolizine (32xxxiii): mp 145-148 °C (hexane); 26.2% yield. Anal. (C31H30N2O5‚0.3H2O) C, H, N. 1,3-Bis-(o-phenylbenzyl)-8-((carbomethoxymethyl)oxy)2-cyclopropylindolizine: mp 194-195 °C; 5.2% yield. Anal. (C42H39NO3‚0.3H2O) C, H, N. 8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(m-phenylbenzyl)indolizine (32xxxiv), 8-((Carbomethoxymethyl)oxy)2-ethyl-3-(3-phenyl-2-propenyl)indolizine (32xxxv) and 8-((Carbomethoxymethyl)oxy)-2-cyclopropyl-3-(1-naphthylmethyl)indolizine (56j). These products could not be isolated from 1,3-disubstituted indolizine and used in the next preparation without further purification. 2-(2-Alkyl-8-((carbomethoxymethyl)oxy)-3-(substituted methyl)indolizin-1-yl)glyoxylamide (27). General procedure: These compounds were prepared from 32, according to the procedure described for the synthesis of 5a. 2-(8-((Carbomethoxymethyl)oxy)-3-(cyclohexylmethyl)2-cyclopropylindolizin-1-yl)glyoxylamide (27xxx) and carboxylic acid 28xxx: mp 153-157 °C; 53.7% yield. Anal. (C23H28N2O5‚0.4AcOEt) C, H, N.

28xxx: mp 229-234 °C; 79% yield; IR νmax (Nujol) 3434, 3334, 1731, 1650(sh), 1620, 1593 cm-1; 1H NMR (CDCl3) δ 0.41-0.46 (2H, m), 0.91-1.01 (2H, m), 1.08-1.79 (11H, m), 1.89-2.05 (1H, m), 2.85 (2H, d, J ) 6.6 Hz), 4.73 (2H, s), 6.38 (1H, d, J ) 7.4 Hz), 6.59 (1H, br s), 6.71 (1H, t, J ) 7.2 Hz), 7.00 (1H, br s), 7.59 (1H, d, J ) 7.0 Hz). 2-(3-(Biphenyl-2-ylmethyl)-8-((carbomethoxymethyl)oxy)-2-isopropylindolizin-1-yl)glyoxylamide (27xxxi) and carboxylic acid 28xxxi: mp 124-130 °C; 48.6% yield. Anal. (C29H28N2O5‚0.2H2O) C, H, N. 28xxxi: mp 139-141 °C. 59% yield. Anal. (C28H26N2O5‚ 1.3H2O) C, H, N. 2-(2-tert-Butyl-8-((carbomethoxymethyl)oxy)-3-(ophenylbenzyl)indolin-1-yl)glyoxylamide (27xxxii) and carboxylic acid 28xxxii: mp 206-207 °C (EtOAc); 77.6% yield. Anal. (C30H30N2O5‚0.7H2O) C, H, N. 28xxxii: mp 221-222 °C (EtOAc); quantitative yield. Anal. (C29H28N2O5‚0.6C6H6) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-2-cyclopentyl-3-(ophenylbenzyl)indolin-1-yl)glyoxylamide (27xxxiii) and carboxylic acid 28xxxiii: mp 119-121 °C (benzene); 77.6% yield. Anal. (C30H28N2O5‚0.7H2O) C, H, N. 28xxxiii: mp 147-148 °C (EtOAc); 73.4% yield. 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(m-phenylbenzyl)indolin-1-yl)glyoxylamide (27xxxiv) and carboxylic acid 28xxxiv: mp 204-205 °C (EtOAc); 11.5% yield. Anal. (C28H26N2O5‚0.2H2O) C, H, N. 28xxxiv: mp 241-244 °C (EtOAc); 73.5% yield. 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(3-phenyl2-propenyl)indolin-1-yl)glyoxylamide (27xxxv) and carboxylic acid 28xxxv: mp 260-262 °C (EtOAc); 73.7% yield; IR νmax (Nujol) 3350, 3199, 1754, 1664, 1611, 1493 cm-1. Anal. (C24H24N2O5‚0.2H2O) C, H, N. 28xxxv: mp 222-224 °C (EtOAc); 71.3% yield. Anal. (C23H22N2O5) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-2-ethyl-3-(3-phenyl2-propanyl)indolin-1-yl)glyoxylamide (27xxxvi) and Carboxylic Acid 28xxxvi. A mixture of the olefin 27xxxv (180 mg, 0.428 mmol) and 10% Pd-C (13 mg) in EtOAc (15 mL) was stirred in hydrogen for 4 h. The catalyst was filtered and washed with EtOAc. The filtrate was concentrated under reduced pressure. The residue was recrystallized from EtOAc to yield 103 mg (56.9%); mp 167 °C. Anal. (C24H26N2O5‚0.1H2O) C, H, N. 28xxxvi: mp 215-217 °C; 93.1% yield. Anal. (C23H24N2O5‚ 0.4H2O) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-2-cyclopropyl-3-(1naphthylmethyl)indolin-1-yl)glyoxylamide (27xxxvii) and carboxylic acid 28xxxvii: amorphous solid; 44.3% yield. Anal. (C27H24N2O5‚0.8C6H6) C, H, N. 28xxxvii: mp 205-207 °C (EtOAc); 70.7% yield. Anal. (C26H22N2O5‚0.4H2O) C, H, N. 8-(Benzyloxy)-1-carbethoxy-2-methoxyindolizine (17c). A mixture of 16b (1 g, 3.69 mmol) and methyl bromoacetate (10 mL) was stirred at 50°C for 18 h in N2. Ether was added to the reaction mixture. The insoluble oil was washed with ether, dried, and concentrated. A mixture of the pyridinium salt and K2CO3 (4.2g, 36.85 mmol) was stirred in 2-butanone (17 mL) at room temperature for 4 h. Dimethyl sulfate (2.5 mL, 26.38 mmol) in 2-butanone (3 mL) was added, then the mixture was heated to 60 °C. Water was added. The mixture was extracted with EtOAc. The extracts were dried. After removal of the solvent, the residue was chromatographed in hexane:EtOAc 5:1 to give 17c: 382 mg (32% yield); IR νmax (neat) 2970, 1693, 1555, 1527, 1452, 1370, 1304 cm-1; 1H NMR (CDCl3) δ 1.11 (3H, t, J ) 7.0 Hz), 3.86 (3H, s), 4.12 (2H, q, J ) 7.0 Hz), 5.15 (2H, s), 6.30 (1H, d, J ) 7.8 Hz), 6.46 (1H, dd, J ) 6.6, J ) 7.8 Hz), 7.26-7.54 (5H, m). 2-(8-(Benzyloxy)-2-methoxy-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (25xxxviii): mp 183-184 °C (hexane:EtOAc). Anal. (C31H26N2O4 0.2H2O) C, H, N. 2-(8-((Carbomethoxymethyl)oxy)-2-methoxy-3-(ophenylbenzyl)indolizin-1-yl)glyoxylamide (27xxxviii) and carboxylic acid 28xxxviii: mp 188-189 °C (hexane:EtOAc). 56% yield (two steps). Anal. (C27H24N2O6‚0.2H2O) C, H, N.

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28xxxviii: mp 197-198 °C (EtOAc); 32% yield. Anal. (C26H22N2O6) C, H, N. Diethyl 2-(3-Benzyloxypyridinio)-3-thionio-4-thiahept2-enedioate (33). A solution of benzyloxypyridine (21.73 g, 0.117 mol) and ethyl bromoacetate (19.6 g, 0.117 mol) in benzene (85 mL) was stirred at 65 °C for 2 h and concentrated. The residue was washed with EtOAc. A solution of aqueous NaOH (11.80 g, 0.295 mol, 35 mL) was added dropwise to a solution of the residue, CS2 (10.8 g, 0.142 mol), water (24 mL), and EtOH (120 mL). The mixture was stirred for 30 min. Ethyl acrylate (11.8 g, 0.118 mol) was added dropwise. The mixture was stirred for 1 h. Ice water was added. The solid was collected by filtration, washed with water, dried (10.9 g, 20.8%), and recrystallized from CHCl3: ether: mp 162-164 °C; IR νmax (Nujol) 1719, 1644 cm-1; 1H NMR (CDCl3) δ 1.16 (3H, t, J ) 6.9 Hz), 1.26 (3H, t, J ) 7.2 Hz), 2.80 (2H, t, J ) 7.5 Hz), 3.58 (2H, t, J ) 7.5 Hz), 4.13 (2H, q, J ) 6.9 Hz), 4.15 (2H, q, J ) 7.2 Hz), 5.21 (2H, s), 7.42 (5H, s), 7.73 (1H, dd, J ) 9.0, 6.0 Hz), 7.87 (1H, ddd, J ) 8.7, 2.4, 1.2 Hz), 8.12 (1H, dt, J ) 6.0, 1.2 Hz), 8.22 (1H, dd, J ) 2.1, 0.9 Hz). Anal. (C22H25NO5S2‚0.05CHCl3‚0.3H2O) C, H, N, S, Cl. 8- and 6-(Benzyloxy)-1,3-dicarbethoxy-2-(2-(carbethoxyethyl)thio)indolizine (34a + 34b). A solution of ethyl bromoacetate (2.70 g, 16.2 mmol) and the salt 33 (6.03 g, 13.5 mmol) in CHCl3 (40 mL) was allowed to stand for 3 d and cooled in ice. A solution of DBU (2.47 g, 16.2 mmol) and chloranil (3.32 g, 13.5 mmol) was added. The mixture was stirred at 0 °C for 6 h and chromatographed (120 g) in CHCl3 to give a ca. 10:1 mixture of 34a and 34b, (6.0 g, 89.1%) as an oil. 8-(Benzyloxy)-1,3-dicarbethoxy-2-mercaptoindolizine (35a). KOtBu (2.73 g, 24.3 mmol) was added in small portions to a solution of the ester 34a+b (9.88 g, 19.8 mmol) in DMF (25 mL) with cooling in ice. The mixture was stirred at 50 °C for 5 h. Ice water and then dilute HCl were added. The mixture was extracted with EtOAc. The extracts were washed with water, dried, and concentrated. The residue was chromatographed (200 g) in hexane:EtOAc (2:1). Both fractions of larger and smaller Rf values were crystallized from benzene:hexane. 35a, the fraction having the larger Rf value: mp 125-127 °C; 1.12 g (16.7%); IR νmax (Nujol) 1661, 1508 cm-1; 1H NMR (CDCl3) δ 1.46 (3H, t, J ) 6.9 Hz), 1.48 (3H, t, J ) 7.5 Hz), 4.42 (2H, q, J ) 6.9 Hz), 4.46 (2H, q, J ) 7.2 Hz), 5.09 (2H, s), 7.04 (1H, s), 7.15 (1H, dd, J ) 9.9, 2.4 Hz), 7.3-7.55 (5H, m), 8.09 (1H, dd, J ) 9.6, 0.6 Hz), 9.41 (1H, s). Anal. (C21H21NO5S) C, H, N, S. The fraction having the smaller Rf value: mp 81-82 °C; 4.59 g (58.1%); IR νmax (Nujol) 1686, 1655, 1543, 1493 cm-1; 1H NMR (CDCl ) δ 1.10 (3H, t, J ) 6.9 Hz), 1.47 (3H, t, J ) 3 7.2 Hz), 4.45 (2H, q, J ) 7.5 Hz), 5.16 (2H, s), 5.56 (1H, s), 6.58 (1H, d, J ) 7.5 Hz), 6.73 (1H, t J ) 6.9 Hz), 7.3-7.5 (5H, m), 9.15 (1H, dd, J ) 7.2, 0.9 Hz). Anal. (C21H21NO5S‚0.4H2O) C, H, N, S. 8-(Benzyloxy)-1,3-dicarbethoxy-2-(methylthio)indolizine (35b). NaH (60%, 76 mg) was added to a solution of the thiol 35a (690 mg, 1.73 mmol) in DMF (4 mL) with cooling in ice under N2. A solution of iodomethane (295 mg, 2.08 mmol) in DMF (1 mL) was added dropwise to the mixture with cooling in ice. The mixture was stirred at room temperature for 2 h, acidified with dilute HCl, and extracted with EtOAc. The extracts were washed with water, dried, and concentrated. The residue was chromatographed in hexane: EtOAc (5:1 to 3:2) to give 732 mg of an oil (quantitative yield): 1H NMR (CDCl3) δ 1.13 (3H, t, J ) 6.9 Hz), 1.45 (3H, t, J ) 7.2 Hz), 2.47 (3H, s), 4.00 (2H, q, J ) 7.2 Hz), 4.45 (2H, q, J ) 7.5 Hz), 5.13 (2H, s), 6.46 (1H, d, J ) 7.5 Hz), 6.70 (1H, t J ) 7.2 Hz), 7.3-7.5 (5H, m), 9.06 (1H, dd, J ) 6.9, 0.6 Hz). 8- and 6-(Benzyloxy)-2-(methylthio)indolizine (24g). Aqueous KOH (10%, 5 mL) was added to a solution of the diester 35b (337 mg, 0.815 mmol) in DMSO (5 mL). The mixture was heated under reflux for 8 h. After cooling, the mixture was acidified with dilute HCl with cooling in ice and extracted with EtOAc. The extracts were washed with water,

dried, and concentrated to give a mixture of 24g and the dicarboxylic acid. The solid in toluene (5 mL) was heated under reflux for 1 h and concentrated. The residue was chromatographed (25 g) in hexane:EtOAc (5:1) and crystallized from hexane: 191 mg (87.0%); mp 94 °C. Anal. (C16H15NOS‚0.05C6H6) C, H, N, S. 2-(8-(Benzyloxy)-2-(methylthio)-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (25xxxix): mp 199-201 °C; 28.5% Yield from 24g. Anal. (C31H26N2O3S) C, H, N, S. 2-(8-Hydroxy-2-(methylthio)-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (26xxxix). A 1 N solution of BBr3 in CH2Cl2 (0.7 mL, 0.7 mmol) was added to a solution of the benzyl ether 25xxxix (85 mg, 0.168 mmol) in CH2Cl2 (1 mL) with cooling in ice. The mixture was stirred at 0 °C for 1 h. Ice water was added. The mixture was extracted with CH2Cl2:MeOH. The extracts were washed with water, dried, and concentrated. The residue was recrystallized from EtOAc (mp 138-142 °C). 2-(8- and 6-((Carbomethoxymethyl)oxy)-2-(methylthio)3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (27xxxix) and carboxylic acid 28xxxix: mp 88-91 °C; 41.3% yield. 28xxxix: mp 200-205 °C; 65.4% yield. Anal. (C26H22N2O5S) C, H, N, S. 2-Ethyl-7-methoxyindolizine (37a) and 2-Cyclopropyl7-methoxyindolizine (37b). 4-Methoxypicoline was treated as in the procedure for the preparation of 24 from 23. 37a: 29.4% yield; IR νmax (KBr) 2962, 1648 cm-1; 1H NMR (CDCl3) δ 1.27 (3H, t, J ) 7.2 Hz), 2.67 (2H, q, J ) 7.4 Hz), 3.77 (3H, s), 6.06 (1H, s), 6.14 (1H, dd, J ) 7.6, 2.6 Hz), 6.52 (1H, d, J ) 2.4 Hz), 6.94 (1H, s), 7.66 (1H, d, J ) 7.6 Hz). MS m/z 175.0982 [M]+. 37b: mp 101-102 °C (hexane); 27.3% yield. Anal. (C12H13NO) C, H, N. 2-Alkyl-7-methoxy-3-(substituted carbonyl)indolizine (38). Indolizine compound 37 was converted to 38 by the same procedure cited for the preparation of 11 from 10. 3-Benzoyl-2-ethyl-7-methoxyindolizine (38a): mp 105106 °C (hexane); 70.5% yield; IR νmax (KBr) 3057, 2966, 2926, 2868, 1645 cm-1; 1H NMR (CDCl3) δ 1.02 (3H, t, J ) 7.5 Hz), 2.17 (2H, q, J ) 7.5 Hz), 3.88 (3H, s), 6.23 (1H, s), 6.54 (1H, dd, J ) 2.7, 7.8 Hz), 6.72 (1H, d, J ) 2.1 Hz), 7.40-7.49 (3H, m), 7.56-7.60 (2H, m), 9.67 (1H, d, J ) 7.5 Hz). Anal. (C18H17NO2‚0.5H2O) C, H, N. 2-Cyclopropyl-7-methoxy-3-(o-phenylbenzoyl)indolizine (38b): a yellow oil; quantitative yield; 1H NMR (CDCl3) δ 0.48 -0.69 (2H, m), 1.11 (1H, m), 3.82 (3H, s), 5.71 (1H, s), 6.45 (1H, dd, J ) 2.8, 7.6 Hz), 6.57 (1H, d, J ) 2.6 Hz), 7.157.54 (9H, m), 9.76 (1H, d, J ) 7.6 Hz). 2-Ethyl-7-methoxy-3-(o-phenylbenzoyl)indolizine (38c): mp 140-141 °C (ether); 90.2% yield. Anal. (C24H23NO) C, H, N. 3-(Cyclohexylcarbonyl)-2-ethyl-7-methoxyindolizine (38d): mp 112-113 °C (hexane); 41.1% yield; IR νmax (KBr) 2923, 2848, 1644 cm-1. Anal. (C18H23NO2‚0.1H2O) C, H, N. 3-Benzyl-2-ethyl-7-methoxyindolizine (39a): amorphous solid; 22.0% yield; IR νmax (KBr) 3002, 2956, 2926, 1646 cm-1; 1H NMR (CDCl ) δ 1.27 (3H, dt, J ) 7.5, 1.2 Hz), 2.69 (2H, q, 3 J ) 7.5 Hz), 3.76 (3H, s), 4.20 (2H, s), 6.09 (1H, dd, J ) 2.4, 7.5 Hz), 6.18 (1H, s), 6.59 (1H, d, J ) 2.1 Hz), 7.04 (2H, d, J ) 7.2 Hz), 7.14-7.27 (3H, m), 7.25 (1H, d, J ) 7.2 Hz). 2-Cyclopropyl-7-methoxy-3-(o-phenylbenzyl)indolizine (39b): mp 109-110 °C (hexane); 44.3% yield. Anal. (C25H23NO) C, H, N. 2-Ethyl-7-methoxy-3-(o-phenylbenzyl)indolizine (39c): mp 100-101 °C (hexane); 39.2% yield. Anal. (C24H23NO) C, H, N. 3-(Cyclohexylmethyl)-2-ethyl-7-methoxyindolizine (39d): amorphous yellow solid; 48.2% yield. 2-(3-Benzyl-2-ethyl-7-methoxyindolizin-1-yl)glyoxylamide (40a): amorphous solid; 78.9% yield; IR νmax (KBr) 3500, 3386, 3004, 2962, 1689, 1644, 1601 cm-1; 1H NMR (CDCl3) δ 1.23 (3H, dt, J ) 7.5, 1.2 Hz), 2.98 (2H, q, J ) 7.8 Hz), 3.87 (3H, s), 4.21 (2H, s), 5.57 (1H, br s), 6.42 (1H, dd, J ) 2.7, 7.5 Hz), 6.79 (1H, br s), 7.08 (1H, d, J ) 6.9 Hz), 7.21 (3H, m), 7.51 (1H, d, J ) 7.5 Hz), 7.82 (1H, d, J ) 2.7 Hz).



2-(2-Cyclopropyl-7-methoxy-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (40b): mp 194-195 °C (benzene: hexane); 50.1% yield. Anal. (C27H24N2O3) C, H, N. 2-(2-Ethyl-7-methoxy-3-(o-phenylbenzyl)indolizin-1yl)glyoxylylamide (40c): mp 101-106 °C (benzene:hexane); 75.9% yield. Anal. (C26H24N2O3‚0.3C6H6) C, H, N. 2-(3-(Cyclohexylmethyl)-2-ethyl-7-methoxyindolizin-1yl)glyoxylamide (40d): mp 178-180 °C (THF:hexane); 50.4% yield. Anal. (C20H25N2O3‚0.2THF) C, H, N. 2-(3-Benzyl-2-ethyl-7-hydroxyindolizin-1-yl)glyoxylamide (41a): amorphous solid; 49% yield; 1H NMR (CDCl3) δ 1.11 (3H, t, J ) 7.2 Hz), 2.86 (2H, t, J ) 7.2 Hz), 4.24 (2H, s), 6.52 (1H, dd, J ) 2.1, 7.5 Hz), 7.08-7.30 (6H, m), 7.43 (1H, d, J ) 2.4 Hz), 7.51 (1H, s), 7.92 (1H, d, J ) 6.9 Hz), 7.98 (1H, s). 2-(2-Cyclopropyl-7-hydroxy-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (41b): amorphous solid; 12.6% yield. 2-(2-Ethyl-7-hydroxy-3-(o-phenylbenzyl)indolizin-1yl)glyoxylylamide (41c): mp 125-129 °C (benzene:hexane); 36.9% yield. Anal. (C25H22N2O3‚0.2C6H6‚0.5H2O) C, H, N. 2-(3-(Cyclohexylmethyl)-2-ethyl-7-hydroxyindolizin-1yl)glyoxylamide (41d): amorphous solid; 28.0% yield. 2-(3-Benzyl-7-((3-carbethoxypropyl)oxy)-2-ethylindolizin-1-yl)glyoxylamide (42a) and carboxylic acid 43a: mp 146-149 °C; 54.% yield; IR νmax (KBr) 3430, 3170, 2958, 2928, 1731, 1674, 1645 cm-1; 1H NMR (CDCl3) δ 1.22 (3H, t, J ) 7.5 Hz), 1.25 (3H, t, J ) 7.2 Hz), 2.13 (2H, m), 2.49 (2H, q, J ) 7.2 Hz), 2.97 (2H, q, J ) 7.5 Hz), 4.08 (2H, t, J ) 6.3 Hz), 4.14 (2H, q, J ) 7.2 Hz), 4.21 (2H, s), 5.56 (1H, br s), 6.40 (1H, dd, J ) 2.7, 7.2 Hz), 6.78 (1H, br s), 7.08 (2H, d, J ) 7.8 Hz), 7.217.29 (3H, m), 7.50 (1H, d, J ) 7.2 Hz), 7.78 (1H, d, J ) 2.7 Hz). Anal. (C25H28N2O3‚0.2H2O) C, H, N. 43a: mp 178-183 °C (dec); 77.0% yield; IR νmax (KBr) 37002400, 3085, 2925, 1710, 1644 cm-1; 1H NMR (CDCl3) δ 1.22 (3H, t, J ) 7.5 Hz), 2.14 (2H, t, J ) 6.9 Hz), 2.97 (2H, q, J ) 7.5 Hz), 4.11 (2H, t, J ) 6.3 Hz), 4.20 (2H, s), 6.38 (1H, br s), 6.41 (1H, dd, J ) 7.2, 2.4 Hz), 6.96 (2H, br s), 7.08 (2H, d, J ) 6.9 Hz), 7.23-7.26 (3H, m), 7.51 (1H, d, J ) 7.5 Hz), 7.75 (1H, d, J ) 2.7 Hz). Anal. (C23H24N2O3‚0.3H2O) C, H, N. 2-(7-((3-Carbethoxypropyl)oxy)-2-cyclopropyl-3-(ophenylbenzyl)indolizin-1-yl)glyoxylamide (42b) and carboxylic acid 43b: amorphous solid; 84.2% yield. 43b: mp 112-121 °C, (dec); 69.6% yield. Anal. (C30H28N2O5‚ 1.2H2O) C, H, N. 2-(7-((3-Carbethoxypropyl)oxy)-2-ethyl-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylylamide (42c) and carboxylic acid 43c: mp 131-133 °C (benzene:hexane); 70.9% yield. Anal. (C31H32N2O5‚0.2H2O) C, H, N. (43c): mp 112-116 °C (dec); 67.0% yield. Anal. (C29H28N2O5‚ 0.9H2O) C, H, N. 2-(7-((3-Carbethoxypropyl)oxy)-3-(cyclohexylmethyl)2-ethyl-hydroxyindolizin-1-yl)glyoxylamide (42d) and carboxylic acid 43d: mp 150-151 °C (THF:hexane); 87.0% yield. Anal. (C25H34N2O5) C, H, N. 43d: mp 201-202.5 °C; 92.4% yield. Anal. (C23H30N2O5‚ 0.3H2O) C, H, N. 2-(7-((Carbethoxymethyl)oxy)-2-ethyl-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (42e) and carboxylic acid 43e: mp 119-121 °C (THF:hexane); 86.6% yield. Anal. (C29H28N2O5‚0.3H2O) C, H, N. 43e: mp 226 °C (dec); 81.0% yield. Anal. (C27H24N2O5‚ 0.3EtOAc‚0.7H2O) C, H, N. 2-(7-((5-Carbethoxypentyl)oxy)-2-ethyl-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (42f) and carboxylic acid 43f: mp 122-123 °C (MeOH:Et2O:hexane); 81.0% yield. Anal. (C32H34N2O5‚0.3H2O) C, H, N. 43f: mp 84-94 °C (dec); 72.0% yield. Anal. (C30H30N2O5‚ 0.9H2O) C, H, N. 2-(7-((2-Carboxyethyl)oxy)-2-ethyl-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (43g). Propiolactone (25 mg, 0.336 mmol) was added dropwise to a solution of 41c (133.7 mg, 0.336 mmol) and KOt-Bu (37.6 mg, 0.336 mmol) in THF (4 mL) under N2. The mixture was stirred for 21 h. Water was added. The mixture was washed with EtOAc. The aqueous phase was acidified with HCl. The precipitate was

collected with filtration to give 43g: 96.2 mg (60.9%); mp 99108 °C (dec). Anal. (C28H26N2O5‚1.2H2O) C, H, N. 2-(7-((3-Carbethoxypropyl)oxy)-2-ethyl-3-(o-phenylbenzyl)indolizin-1-yl)acetamide (44a) and Carboxylic Acid 44b. BH3-t-BuNH2 complex (125 mg, 1.44 mmol) was added to a mixture of AlCl3 (13 mg, 0.097 mmol) in toluene (10 mL) with cooling in ice. The mixture was stirred at 0 °C for 10 min. A solution of the glyoxylamide 42c (246 mg, 0.48 mmol) in toluene (5 mL) was added to the solution. The solution was heated at 60 °C for 2 h. After cooling, the solution was poured to ice-cold dilute HCl. The mixture was extracted with CH2Cl2. The extracts were washed with water, dried, and concentrated. The residue was chromatographed in EtOAc:hexane (4:1) and recrystallized from hexane: 190 mg (79.4%); mp 128-130 °C. Anal. (C31H34N2O4‚0.6H2O) C, H, N. 44b: mp 105-120 °C (dec); 62.0% yield. Anal. (C31H34N2O4‚ 0.6H2O) C, H, N. 3-((Benzyloxycarbonyl)amino)-2-methylpyridine (45b). A mixture of 3-aminopicoline 45a (0.60 g, 5.5 mmol), N(benzyloxycarbonyl)succinimide (2.1 g, 8.3 mmol), and DMF (2 mL) was left for 2 d. The reaction mixture was poured into water, extracted with EtOAc, washed with water, and dried. The solvent was removed. The residue was chromatographed by eluting with EtOAc:hexane to give 45b (0.92 g, 68%), mp 76-78 °C; IR νmax (Nujol) 1725, 1551, 1227, 1061 cm-1; 1H NMR (CDCl3) δ 2.49 (3H, s), 5.22 (3H, s), 7.16 (1H, m), J ) 8.7 Hz), 7.36-7.45 (5H, m), 8.15-8.27 (2H, m). Anal. (C14H14N2O2) C, H, N. 3-(N-(Benzyloxycarbonyl)-N-((methoxycarbonyl)methyl)amino)-2-methylpyridine (46). To a suspension of NaH (60% dispersion in oil, 0.17 g, 4.2 mmol) in DMF (3 mL) was added 45b (0.92 g, 3.8 mmol) in DMF (5 mL) at 0 °C with stirring under N2. Stirring was continued for 1 h, at which time methyl bromoacetate (0.40 mL, 4.2 mmol) was added. The reaction mixture was stirred at room temperature for an additional 2.5 h. The reaction mixture was poured into water, extracted with EtOAc, washed with water, and dried. The solvent was removed. The product was purified by column chromatography in EtOAc:hexane (1:1) to yield 46 (1.07 g, 90%) as a yellow oil: 1H NMR (CDCl3) δ 2.43 (3/4H, s), 2.51 (1/4H, m), 3.68 (1/4H, m), 3.76 (3/4H, s), 3.85 (1H, d, J ) 18 Hz), 4.69 (1H, d, J ) 18 Hz), 5.06-5.21 (3/2H, m), 5.22 (1/2H, s), 7.13-7.37 (6H, m), 7.73 (1H, m), 8.45 (1H, m). 3-Benzyl-8-(N-(benzyloxycarbonyl)-N-((methoxycarbonyl)methyl)amino)-2-methylindolizine (32xl): 42% yield; 1H NMR (CDCl ) δ 2.34 (3H, s), 3.67-3.77 (3H, m), 4.21-4.46 3 (4H, m), 5.15 (2/3H, s), 5.25 (1/3H, s), 6.28-6.37 (2H, m), 6.77 (1H, m), 7.04-7.50 (11H, m). 8-(N-(Benzyloxycarbonyl)-N-((methoxycarbonyl)methyl)amino)-3-(cyclohexylmethyl)-2-methylindolizine (32xli): 31% yield; 1H NMR (CDCl3) δ 0.82-1.80 (11H, m), 2.25 (3H, s), 2.70 (2H, d, J ) 7 Hz), 3.66 (3/4H, s), 3.74 (9/4H, s), 4.10-4.55 (2H, m), 5.15 (3/2H, s), 5.23 (1/2H, s), 6.19 (3/4H, s), 6.23 (1/4H, s), 6.43 (1H, m), 6.73 (3/4H, d, J ) 7 Hz), 6.79 (1/4H, d, J ) 7 Hz), 7.12-7.42 (5H, m), 7.64 (1H, d, J ) 7 Hz). 2-(3-Benzyl-8-(N-(benzyloxycarbonyl)-N-((methoxycarbonyl)methyl)amino)-2-methylindolizin-1-yl)glyoxylamide (27xl): 66% yield; 1H NMR (CDCl3) δ 2.44 (1H, s), 2.45 (2H, s), 3.67 (1H, s), 3.73 (2H, s), 3.80 (1H, d, J ) 18 Hz), 4.24 (2H, s), 4.71 (1H, d, J ) 18 Hz), 5.00-5.31 (2H, m), 6.64 (1H, m), 7.04-7.42 (11H, m), 7.62 (1H, m). 2-(8-(N-(benzyloxycarbonyl)-N-((methoxycarbonyl)methyl)amino)-3-(cyclohexylmethyl)-2-methylindolizin1-yl)glyoxylamide (27xli): 72% yield; 1H NMR (CDCl3) δ 1.00-1.26 (4H, m), 1.50-1.78 (7H, m), 2.32 (1H, s), 2.33 (2H, s), 2.70 (2H, d, J ) 7 Hz), 3.67 (1H, s), 3.73 (2H, s), 3.78 (2/ 3H, d, J ) 18 Hz), 3.79 (1/3H, d, J ) 18 Hz), 4.60 (1/3H, d, J ) 18 Hz), 4.69 (2/3H, d, J ) 18 Hz), 5.03 (2/3H, d, J ) 13 Hz), 5.19 (1/3H, d, J ) 13 Hz), 5.23 (2/3H, d, J ) 13 Hz), 5.25 (1/ 3H, d, J ) 13 Hz), 6.73 (2/3H, t, J ) 7 Hz), 6.79 (1/3H, t, J ) 7 Hz), 7.14-7.43 (6H, m), 7.79 (1H, m). 2-(3-Benzyl-8-((methoxycarbonyl)methyl)amino)-2methylindolizin-1-yl)glyoxylamide (47xl) and Carboxylic Acid 28xl. A mixture of the indolizine 27xl (88 mg, 0.17

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mmol) and 10% Pd-C (0.02 g) in EtOAc (5 mL) was stirred in H2 atmosphere for 3 h. The catalyst was filtered and the filtrate was concentrated. Crystallization of the residue from THF:ether afforded 47xl (51 mg, 78%): mp 186-188 °C. Anal. (C21H21N3O4) C, H, N. 28xl: mp 293 °C (dec) (MeOH:ether); 61% yield. 2-(8-((methoxycarbonyl)methyl)amino)-3-(cyclohexylmethyl)-2-methylindolizin-1-yl)glyoxylamide (47xli) and carboxylic acid 28xli: mp 173-177 °C (MeOH:ether:hexane); 90% yield. Anal. (C21H27N3O4‚0.2H2O) C, H, N. 28xl: mp >300 °C (MeOH:ether); 47% yield. 2-(3-Benzyl-8-((methoxycarbonyl)methyl)amino)-2methylindolizin-1-yl)acetamide (48a) and carboxylic acid 48b: mp 147-150 °C (dec) (EtOH:ether:hexane); 55% yield. 48b: 60% yield. 2-(3-(Biphenyl-2-ylmethyl)-2-ethyl-8-(substituted methyloxy)indolizin-1-yl)glyoxylamide (49a-e). General procedure: 2-(3-(Biphenyl-2-ylmethyl)-2-ethyl-8-((hydroxymethyl)oxy)indolizin-1-yl)glyoxylamide (26ii) was treated with the same procedure as for the preparation of 27 from 26. 2-(3-(Biphenyl-2-yl-methyl)-2-ethyl-8-(((2-trityltetrazolyl)methyl)oxy)indolizin-1-yl)glyoxylamide (49a): mp 119-121 °C; 66% yield; IR νmax (Nujol) 3439, 3363, 3166, 1734, 1685, 1607, 1495, 1249 cm-1; 1H NMR (CDCl3) δ 1.17 (3H, t, J ) 7.5 Hz), 2.78 (2H, q, J ) 7.5 Hz), 4.10 (2H, s), 4.85 (1H, br s), 5.42 (2H, s), 6.05 (1H, br s), 6.45 (1H, t, J ) 7.2 Hz), 6.58 (1H, d, J ) 7.2 Hz), 6.77 (1H, d, J ) 7.5 Hz), 7.03 (1H, d, J ) 6.9 Hz), 7.08-7.18 (7H, m), 7.22-7.54 (16H, m). 2-(3-(Biphenyl-2-ylmethyl)-2-ethyl-8-((tetrazolylmethyl)oxy)indolizin-1-yl)glyoxylamide (49b). mp 206209 °C (dec); 60% yield. Anal. (C27H24N6O3‚0.1H2O) C, H, N. 2-(3-(Biphenyl-2-ylmethyl)-2-methyl-8-(pyridin-2-ylmethoxy)indolizin-1-yl)glyoxylamide (49c): mp 196-197 °C (hexane:AcOEt); 4.2% yield; 1H NMR (CDCl3) δ 2.38 (3H, s), 4.11 (2H, s), 4.81 (1H, br s), 5.11 (2H, s), 6.13 (1H, br s), 6.35 (1H, d, J ) 7.5 Hz), 6.44 (1H, t, J ) 7.2 Hz), 6.81 (1H, d, J ) 7.2 Hz), 7.02 (1H, d, J ) 6.0 Hz), 7.14-7.20 (1H, m), 7.257.33 (1H, m), 7.35-7.55 (9H, m). 2-(3-(Biphenyl-2-ylmethyl)-2-methyl-8-(pyridin-4-ylmethoxy)indolizin-1-yl)glyoxylamide (49d): mp 195-197 °C (hexane:AcOEt); 3.4% yield. 2-(3-(Biphenyl-2-ylmethyl)-2-methyl-8-(quinolin-2-ylmethoxy)indolizin-1-yl)glyoxylamide (49e): mp 165-167 °C (hexane:AcOEt); 3.4% yield; 1H NMR (CDCl3) δ 2.41 (3H, s), 4.11 (2H, s), 5.31 (1H, br s), 5.47 (2H, s), 6.26-6.38 (2H, m), 6.51 (1H, br s), 6.83 (1H, d, J ) 7.8 Hz), 6.98-7.01 (1H, m), 7.14-7.24 (1H, m), 7.25-7.31 (3H, m), 7.40-7.60 (5H, m), 7.69-7.82 (3H, m), 8.04-8.17 (2H, m). 2-(8-((3-Carbomethoxypropyl)oxy)-2-ethyl-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (49f) and carboxylic acid 49g: mp 126-127 °C; 42% yield. Anal. (C31H32N2O5‚ 0.5H2O) C, H, N. 49g: mp 185-187 °C; 71% yield. Anal. (C29H28N2O5‚0.3H2O) C, H, N. 2-(8-((2-Carboxyethyl)oxy)-2-ethyl-3-(o-phenylbenzyl)indolizin-1-yl)glyoxylamide (49h): mp 185-187 °C; 11% yield; 2-(8-((Cyanomethyl)oxy)-2-ethyl-3-(1-naphthylmethyl)indolizin-1-yl)glyoxylamide (50a): mp 212-215 °C (ether); 45% yield. Anal. (C21H18N3O3Cl) C, H, N. 2-(8-((Cyanomethyl)oxy)-2-ethyl-3-(1-naphthylmethyl)indolizin-1-yl)glyoxylamide (50b). A mixture of the nitrile derivative 50a (100 mg, 0.253 mmol) and trimethyltin azide (68 mg, 0.329 mmol) in toluene (2.5 mL) was heated under reflux for 23 h. The precipitate was collected by filtration and suspended in toluene (2 mL). HCl gas was introduced. The mixture was stirred at room temperature for 20 min and then concentrated. EtOAc was added. The mixture was extracted with 1 N KOH. The aqueous phase was washed with CH2Cl2, acidified with dilute HCl, and extracted with EtOAc. The extracts were washed with water and dried. After removal of the solvent, the residue was dissolved in ether. The insoluble materials were removed by filtration and hexane was added to the filtrate to give 50b (25 mg, 23% yield): mp 140-143 °C (dec) (ether:hexane).

2-(3-Benzyl-8-((carboxymethyl)oxy)-2-ethylindolizin1-yl)-N-methylglyoxylamide (51a): mp 212-213 °C (AcOEt); 47% yield; IR νmax (KBr) 3361, 2965, 2931, 1766, 1609, 1308, 1093 cm-1; 1H NMR (CDCl3) δ 1.22 (3H, t, J ) 7.6 Hz), 2.87 (2H, q, J ) 7.6 Hz), 3.05 (3H, d, J ) 5.4 Hz), 4.26 (2H, s), 4.73 (2H, s), 6.39 (1H, d, J ) 7.6 Hz), 6.59 (1H, dd, J ) 6.4, 7.6 Hz), 7.66-7.11 (2H, m), 7.22-7.29 (3H, m), 7.42 (1H, d, J ) 6.4 Hz). Anal. (C22H22N2O5) C, H, N. (3-Benzyl-8-((carboxymethyl)oxy)-2-ethylindolizin-1yl)N,N-dimethylglyoxylamide (51b): mp 166-167 °C (AcOEt); 49% yield; IR νmax (KBr) 3435, 2937, 1764, 1608, 1195 cm-1; 1H NMR (CDCl3) δ 1.24 (3H, t, J ) 7.6 Hz), 2.99 (2H, q, J ) 7.6 Hz), 3.15 (3H, s), 4.26 (2H, s), 4.21 (3H, s), 4.27 (2H, s), 4.74 (2H, s), 6.50 (1H, d, J ) 8.0 Hz), 6.63 (1H, dd, J ) 6.4, 8.0 Hz), 7.05-7.10 (2H, m), 7.22-7.29 (3H, m), 7.44 (1H, d, J ) 6.4 Hz). Anal. (C23H24N2O5‚0.9H2O) C, H, N. 3-(4-Methoxyphenyl)-2-methylacrylic Acid (53a): A mixture of p-anisaldehyde (26.6 g, 0.195 mol), propionic anhydride (43.0 mL, 0.347 mol) and sodium propionate (18.8 g, 0.195 mol) was heated at 150 °C overnight. After cooling, the reaction mixture was basified with 4N NaOH and washed with ether. The aqueous phase was acidified with conc. HCl and the precipitate was filtered to yield 53a, 28.5 g (76%), mp 152155 °C. 1H NMR (CDCl3) δ 2.16 (3H, d, J ) 1.2 Hz), 3.85 (3H, s), 6.95 (2H, d, J ) 8.7 Hz), 7.44 (2H, d, J ) 8.7 Hz), 7.78 (1H, br s); IR νmax (KBr) 1662, 1605, 1570, 1510 cm-1; EIMS m/z 192 (M+, base peak). Anal. (C11H12O3) C, H. 3-(3-Methoxyphenyl)-2-methylacrylic acid (53b): mp 78-79 °C; 93% yield. Anal. (C11H12O3) C, H. 2-Ethyl-3-(3-methoxyphenyl)acrylic acid (53c): mp 8990 °C; 24% yield. Anal. (C12H14O3) C, H. 3-(4-Methoxyphenyl)-2-methylpropionic Acid (54a). A mixture of the acrylic acid 53a (28.3 g, 0.147 mol) and 10% palladium-coal (2.49 g) in methanol (350 mL) was hydrogenated under 3 atm overnight. The catalyst was filtered off and the solvent was evaporated to give 54a (21.2 g, 74%): mp 43-44 °C; 1H NMR (CDCl3) δ 1.17 (3H, d J ) 6.8 Hz), 2.542.83 (2H, m), 3.01 (1H, dd, J ) 5.4, 12.4 Hz), 3.79 (3H, s), 6.83 (2H, d, J ) 8.7 Hz), 7.10 (2H, d, J ) 8.7 Hz); IR νmax (film) 3424, 1709, 1612, 1584 cm-1; EIMS m/z 121 (base peak), 194 (M+). Anal. (C11H14O3) C, H. 3-(3-Methoxyphenyl)-2-methylpropionic acid (54b): 75% yield. Anal. (C11H14O3‚0.1H2O) C, H. 2-(3-Methoxybenzyl)butyric acid (54c): quantitative yield. Anal. (C12H16O3) C, H. 2-(2-Bromo-5-methoxybenzyl)butyric Acid (55). To a solution of the butyric acid 54a (33.9 g, 0.163 mmol) in acetic acid (50 mL) was added a solution of bromine (10.5 mL, 0.204 mmol) in acetic acid (20 mL) at 0 °C. The resulting solution was stirred at room temperature for 2.5 h and then the mixture was partitioned between water and AcOEt. The aqueous layer was extracted with AcOEt, and the combined organic layers were washed with saturated Na2S2O3 and water, dried, and evaporated. The residue 55 (51.8 g) was used to the next preparation without further purification: mp 39-42 °C; 1H NMR (CDCl3) δ 1.00 (3H, t, J ) 7.4 Hz), 1.55-1.83 (2H, m), 2.68-3.08 (3H, m), 3.75 (3H, s), 6.65 (1H, dd, J ) 8.8, 3.0 Hz), 6.78 (1H, d, J ) 3.0 Hz), 7.41 (1H, d, J ) 8.8 Hz). IR νmax (KBr) 3010, 1689, 1593, 1577 cm-1. 4-Bromo-2-ethyl-7-methoxy-1-indanone (56). A mixture of the butyric acid 55 (51.6 g) and polyphosphoric acid (511 g) was heated at 100 °C for 2.5 h. The mixture was poured into water and extracted with AcOEt. The combined extracts were washed with water, 5% NaHCO3, and brine and dried. After removal of the solvent, the residue was chromatographed by eluting with hexane:AcOEt (4:1 to 1:2) to give 56 (30.0 g): 1H NMR (CDCl3) δ 1.02 (3H, s, J ) 7.4 Hz), 1.40-1.66 (1H, m), 1.85-2.10 (1H, m), 2.52-2.76 (2H, m), 3.19 (1H, dd, J ) 18.2, 8.0 Hz), 3.94 (3H, s), 6.72 (1H, d, J ) 8.8 Hz), 7.64 (1H, d, J ) 8.8 Hz); IR νmax (film) 1712, 1585 cm-1; EIMS m/z 240 (base peak), 268 (M+); HR-EIMS calcd for C12H13BrO2 268.0098, found 268.0079. 6-Methoxy-2-methyl-1-indanone (57a). To the propionic acid 54a (21.0 g, 0.108 mol) was added polyphosphoric acid (200 g) at 50 °C. The reaction was maintained at 90 °C for 2 h. The mixture was poured into water, stirred at room



temperature overnight, and extracted with ether. The combined extracts were washed with aqueous NaHCO3 and brine and dried. After removal of the solvent, the residue was chromatographed by eluting with CH2Cl2:MeOH (10:0 to 9:1) and hexane:AcOEt (9:1 to 4:1) to give 57a (7.45 g, 39%): 1H NMR (CDCl3) δ 1.31 (3H, d J ) 7.2 Hz), 2.58-2.84 (2H, m), 3.33 (1H, dd, J ) 16.1, 7.1 Hz), 3.84 (3H, s), 7.15-7.23 (2H, m), 7.30-7.40 (1H, m). 7-Methoxy-2-methyl-1-indanone (57b): 17% yield. Anal. (C11H12O2‚0.1H2O) C, H. 2-Ethyl-7-methoxy-1-indanone (57c): three steps yield 51%; mp 67-69 °C. Anal. (C12H14O2) C, H. Ethyl (6-Methoxy-2-methyl-3H-inden-1-yl)acetate (58a). To a solution of triethyl phosphonoacetate (17.2 g, 76.7 mmol) in toluene (100 mL) was added 60% NaH (3.06 g, 76.5 mmol) at 0 °C. After the reaction mixture was stirred for 1 h at this temperature, a solution of the indanone 57a (1.35 g, 7.63 mmol) in toluene (25 mL) was slowly added. The mixture was refluxed for 4 h and then was poured into 1 N HCl and extracted with AcOEt. The extract was washed with water, dried, and concentrated to produce a crude residue, which was chromatographed by eluting with hexane:AcOEt (19:1) to give the mixture of the compound 58a and its positional isomer (1.65 g, 88%). The mixture was used to the next preparation without further purification: 1H NMR (CDCl3) δ 1.24 (3H, t, J ) 7.2 Hz), 2.12 (3H, s), 3.27 (2H, s), 3.49 (2H, s), 3.83 (3H, s), 4.14 (2H, q, J ) 7.2 Hz), 6.68 (1H, dd, J ) 2.5, 8.1 Hz), 6.86 (1H, d, J ) 2.5 Hz), 7.24 (1H, d, J ) 8.1 Hz). Ethyl (7-methoxy-2-methylinden-1-ylidene)acetate (59b): 49% yield; 1H NMR (CDCl3) δ 1.24 (3H, d, J ) 6.6 Hz), 1.27 (3H, t, J ) 7.0 Hz), 2.50-2.71 (1H, m), 2.93-3.19 (2H, m), 3.81 (3H, s), 4.21 (2H, q, J ) 7.0 Hz), 5.81 (1H, d, J ) 2.0 Hz), 6.70 (1H, d, J ) 8.4 Hz), 6.86 (1H, d, J ) 7.6 Hz), 7.25 (1H, t, J ) 7.8 Hz). Ethyl (2-ethyl-7-methoxyindan-1-ylidene)acetate (59c): 36% yield. Anal. (C16H20O3‚0.1H2O) C, H. Ethyl (2-Bromo-7-methoxy-2-methylindan-1-ylidene)acetate (60b). To a solution of the ester compound 59a (1.39 g, 5.65 mmol) in CCl4 (15 mL) were added NBS (1.11 g, 6.22 mmol) and benzoyl peroxide (68.5 mg, 0.283 mmol). The mixture was stirred at 50 °C for 6 h, filtered, washed with saturated Na2S2O3, and dried. After removal of the solvent, the residue was chromatographed by eluting with hexane: AcOEt (19:1) to afford 60b (0.424 g, 23%): mp 85-91 °C; 1H NMR (CDCl3) δ 1.23 (3H, t, J ) 7.2 Hz), 2.12 (3H, s), 3.42 (2H, s), 3.84 (3H, s), 4.22 (2H, qd, J ) 7.2, 1.0 Hz), 6.02 (1H, s), 6.79 (1H, d, J ) 8.0 Hz), 7.01 (1H, dd, J ) 7.2, 0.8 Hz), 7.13 (1H, t, J ) 7.7 Hz); IR νmax (KBr) 1750, 1580 cm-1; EIMS m/z 199 (base peak), 324 (M+); HR-EIMS calcd for C15H17BrO3 324.0361, found 324.0377. Ethyl (2-Bromo-2-ethyl-7-methoxyindan-1-ylidene)acetate (60c). This compound was used in the next step without purification. Ethyl (7-Methoxy-2-methyl-3H-inden-1-yl)acetate (58b). The mixture of the ester compound 60b (388 mg, 1.19 mmol) and PtO2 (38.4 mg) in AcOH (4.0 mL) was hydrogenated under ordinary atmosphere overnight. The catalyst was filtered off and the solvent was evaporated. The residue was chromatographed by eluting with hexane:AcOEt (97:3 to 9:1) and crystallized from hexane:AcOEt to give 58b (170 mg, 59%): mp 76-79 °C; 1H NMR (CDCl3) δ 1.25 (3H, s, J ) 7.0 Hz), 2.04 (3H, s), 3.32 (2H, s), 3.67 (2H, s), 3.78 (3H, s), 4.16 (2H, q, J ) 7.0 Hz), 6.73 (1H, d, J ) 7.8 Hz), 6.98 (1H, d, J ) 6.6 Hz), 7.06 (1H, t, J ) 7.7 Hz); IR νmax (KBr) 1735, 1578 cm-1; EIMS m/z 172 (base peak), 246 (M+). Anal. (C15H18O3‚0.1H2O) C, H. Ethyl (2-Ethyl-7-methoxy-3H-inden-1-yl)acetate (58c). Method A yielded 32% in two steps. Method B: To a solution of the ester compound 59c (4.15 g, 0.0160 mol) in CHCl3 (40 mL) was added three drops of concentrated H2SO4. The resulting solution was refluxed for 40 min and dried over K2CO3. After removal of the solvent, the residue was chromatographed by eluting with hexane: AcOEt (98:2 to 95:5) to give 58c (3.55 g, 85%). Anal. (C16H20O3‚0.5H2O) C, H.

[(3Z)-Benzylidene-6-methoxy-2-methyl-3H-inden-1-yl]acetic acid (61a). To a solution of the crude indene 58a (1.64 g, 6.66 mmol) in MeOH (20 mL) were added benzaldehyde (1.35 mL, 13.3 mmol) and 1 N NaOMe (20.0 mL, 20 mmol) at room temperature. The resulting solution was refluxed for 160 min, evaporated, poured into 1 N HCl, and extracted with AcOEt. The organic layer was washed with water, dried, and concentrated. The residue was chromatographed by eluting with hexane:AcOEt (9:1) and then CHCl3:MeOH (9:1) and recrystallized (hexane:AcOEt) to afford 61a: 0.841 g (41% yield); mp 146-160 °C; 1H NMR (CDCl3) δ 2.19 (3H, s), 3.59 (2H, s), 3.78 (3H, s), 6.40 (1H, dd, J ) 8.2, 2.4 Hz), 6.75 (1H, d, J ) 2.4 Hz), 7.12 (1H, s), 7.24 (1H, d, J ) 8.2 Hz), 7.307.56 (5H, m); IR νmax (KBr) 3428, , 2834, 1701, 1611, 1582 cm-1; EIMS m/z 306 (M+, base peak). Anal. (C20H18O3‚0.2H2O) C, H. [3(Z)-Benzilidene-7-methoxy-2-methyl-3H-inden-1-yl]acetic acid (61b): mp 165-175 °C; 59% yield. Anal. (C20H18O3‚0.6H2O) C, H. [3(Z)-Benzylidene-2-ethyl-7-methoxy-3H-inden-1-yl]acetic acid (61c): 166-188 °C (dec); 47% yield. Anal. (C21H20O3‚0.4H2O): C, H. (Z)-2-[3-(Biphenyl-2-ylmethylene)-2-ethyl-7-methoxy3H-inden-1-yl]acetic acid (61d): mp 230-232 °C; 39% yield; EIMS m/z 165 (base peak), 396 (M+); HR-EIMS calcd for C27H24O3 396.1774, found 396.1772. (E/Z)-[3-(2-Benzylbenzylidene)-2-ethyl-7-methoxy-3Hinden-1-yl]acetic acid (61e): mp 119.5-136 °C; 62% yield. Anal. (C28H26O3‚0.3H2O) C, H. (Z)-[3-(3-Chlorobenzylidene)-2-ethyl-7-methoxy-3H-inden-1-yl]acetic acid (61f): mp 173-178 °C; 79% yield. Anal. (C21H19O3Cl 0.3H2O) C, H, Cl. (Z)-[3-(2,3-Dichlorobenzylidene)-2-ethyl-7-methoxy3H-inden-1-yl]acetic acid (61g): mp 214.5-222 °C; 63% yield; EIMS m/z 388 (M+, base peak); HR-EIMS calcd for C21H18 O3Cl2 388.0632, found 388.0619. (Z)-(2-Ethyl-7-methoxy-3-(naphthalen-1-ylmethylene)3H-inden-1-yl)acetic acid (61i): mp 188-191 °C; 46% yield. Anal. (C25H22O3) C, H. (Z)-(2-Ethyl-7-methoxy-3-(naphthalen-2-ylmethylene)3H-inden-1-yl)acetic acid (61j): mp 188-192.5 °C; 56% yield. Anal. (C25H22O3) C, H. 2-[3(Z)-Benzylidene-6-methoxy-2-methyl-3H-inden-1yl]acetamide (62a). To a solution of the acetic acid derivatve 61a (200 mg, 0.645 mmol) in CH3CN (10.0 mL) were added Et3N (0.140 mL, 1.00 mmol) and benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (434 mg, 0.981 mmol) at 0 °C. The resulting solution was stirred at room temperature for 45 min, and then 28% NH4OH (0.440 mL) was added. After 30 min, the mixture was poured into 2 N HCl and extracted with AcOEt. The organic layer was washed with water and dried. After removal of the solvent, the residue was chromatographed twice by eluting with CH2Cl2:MeOH (99:1 to 98.5:1.5) and hexane:AcOEt (1:1 to 1:9) to give 62a: 183 mg (92%); mp 174-178 °C; 1H NMR (CDCl3) δ 2.22 (3H, s), 3.55 (2H, s), 3.79 (3H, s), 5.44 (1H, br s), 5.64 (1H, br s), 6.44 (1H, dd, J ) 8.4, 2.4 Hz), 6.73 (1H, d, J ) 2.4 Hz), 7.16 (1H, s), 7.29 (1H, d, J ) 8.4 Hz), 7.32-7.60 (5H, m); IR νmax (KBr) 3389, 3196, 1653, 1614 cm-1; EIMS m/z 305 (M+, base peak). Anal. (C20H19NO2‚0.3H2O) C, H, N. 2-[3(Z)-Benzilidene-7-methoxy-2-methyl-3H-inden-1yl]acetamide (62b): mp 175-177 °C; 96% yield; EIMS m/z 305 (base peak, M+); HR-EIMS calcd for C20H19NO2 305.1414, found 305.1416. 2-[3(Z)-Benzylidene-2-ethyl-7-methoxy-3H-inden-1-yl]acetamide (62c): mp 153-156 °C; 99% yield; EIMS m/z 260 (base peak), 319 (M+). (Z)-2-[3-(Biphenyl-2-ylmethylene)-2-ethyl-7-methoxy3H-inden-1-yl]acetamide (62d): mp 190-200 °C; 91% yield; EIMS m/z 165 (base peak), 395 (M+); HR-EIMS calcd for C27H25NO2 395.1883, found 395.1885. (E/Z)-2-[3-(2-Benzylbenzylidene)-2-ethyl-7-methoxy3H-inden-1-yl]acetamide (62e): mp 133-147 °C; 74% yield; EIMS m/z 409 (M+, base peak). (Z)-2-[3-(3-Chlorobenzylidene)-2-ethyl-7-methoxy-3Hinden-1-yl]acetamide (62f): mp 204-208 °C; 85% yield;

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EIMS m/z 294 (base peak), 353 (M+); HR-EIMS calcd for C21H20 NO2Cl 353.1181, found 353.1160. (Z)-2-[3-(2,3-Dichlorobenzylidene)-2-ethyl-7-methoxy3H-inden-1-yl]acetamide (62g): mp 170-176.5 °C; 81% yield; HR-EIMS calcd for C21H19 NO2Cl2 387.0791, found 387.0798. (Z)-2-[2-Ethyl-7-methoxy-3-(3-(trifluoromethyl)benzylidene)-3H-inden-1-yl]acetamide (62h): mp 205.5-208 °C; 32% yield (two steps). Anal. (C22H20NO2F3) C, H, N, F. (Z)-2-(2-Ethyl-7-methoxy-3-(naphthalen-1-ylmethylene)3H-inden-1-yl)acetamide (62i): mp 172-175.5 °C; 91% yield. Anal. (C25H23 NO2‚0.1H2O) C, H, N. (Z)-2-(2-Ethyl-7-methoxy-3-(naphthalen-2-ylmethylene)3H-inden-1-yl)acetamide (62j): mp 221-223 °C; 80% yield. Anal. (C25H23NO2‚0.3H2O) C, H, N. 2-[3(Z)-Benzylidene-6-hydroxy-2-methyl-3H-inden-1yl]acetamide (63a): 49% yield; mp 178-180 °C; 1H NMR (CDCl3) δ 2.20 (3H, s), 3.56 (2H, s), 5.55 (1H, br s), 5.77 (1H, br s), 6.41 (1H, d, J ) 8.4, 2.4 Hz), 6.69 (1H, d, J ) 2.4 Hz), 7.14 (1H, s), 7.25 (1H, d, J ) 8.4 Hz), 7.30-7.56 (6H, m); IR νmax (KBr) 3212, 1657, 1602 cm-1; EIMS m/z 232 (base peak), 291 (M+). Anal. (C19H17NO2‚0.4H2O) C, H, N. 2-[3(Z)-Benzilidene-7-hydroxy-2-methyl-3H-inden-1-yl]acetamide (63b): mp 200-203 °C; quantitative yield; EIMS m/z 274 (base peak), 291 (M+); HR-EIMS calcd for C19H17NO2 291.1258, found 291.1253. (Z)-2-(3-Benzylidene-2-ethyl-7-hydroxy-3H-inden-1-yl)acetamide (63c): mp 176-180 °C (dec); 87% yield. Anal. (C20H19NO2‚0.8H2O) C, H, N. (Z)-2-[3-(Biphenyl-2-ylmethylene)-2-ethyl-7-hydroxy3H-inden-1-yl]acetamide (63d): mp 168-172 °C; 49% yield. Anal. (C26H23NO2‚0.2H2O) C, H, N. (Z)-2-[3-(2-Benzylbenzylidene)-2-ethyl-7-hydroxy-3Hinden-1-yl]acetamide (63e): mp 137.5-153.5 °C; 72% yield. Anal. (C27H25 NO2‚0.2H2O) C, H, N. (Z)-2-[3-(3-Chlorobenzylidene)-2-ethyl-7-hydroxy-3Hinden-1-yl]acetamide (63f): mp 185-185.5 °C; 79% yield. Anal. (C20H18 NO2Cl‚0.2H2O) C, H, N, Cl. (Z)-2-[3-(2,3-Dichlorobenzylidene)-2-ethyl-7-hydroxy3H-inden-1-yl]acetamide (63g): mp 193-194.5 °C; 90% yield. Anal. (C20H17NO2Cl2) C, H, N, Cl. (Z)-2-[2-Ethyl-7-hydroxy-3-(3-(trifluoromethyl)benzylidene)-3H-inden-1-yl]acetamide (63h): mp 184.5-186 °C; 96% yield. Anal. (C21H18NO2F3) C, H, N, F. (Z)-2-(2-Ethyl-7-hydroxy-3-(naphthalen-1-ylmethylene)3H-inden-1-yl)acetamide (63i): mp 189-189.5 °C; 92% yield. Anal. (C24H21NO2‚0.3H2O) C, H, N. (Z)-2-(2-Ethyl-7-hydroxy-3-(naphthalen-2-ylmethylene)3H-inden-1-yl)-acetamide (63j): mp 200-201.5 °C; 65% yield. Anal. (C24H21NO2‚0.2H2O) C, H, N. Ethyl 4-[[1(Z)-Benzylidene-3-(carbamoylmethyl)-2methyl-1H-inden-5-yl]oxy]butanate (64a). To compound 63a (43.7 mg, 0.150 mmol) in DMF (1.0 mL) was added 60% NaH (21.3 mg, 0.533 mmol). After addition, the mixture was stirred at room temperature for 60 min, and then ethyl 4-bromobutyrate (75 µL, 0.524 mmol) was added. The mixture was stirred at 0 °C for 45 min and then at room temperature for 75 min and partitioned between 1 N HCl and AcOEt. The organic layer was separated, washed with water, dried, filtered, and concentrated. The residue was purified by preparative TLC (200 × 200 × 0.25 mm, elution with AcOEt) to give 64a (38.0 mg, 63%): mp 124-128 °C; 1H NMR (CDCl3) δ 1.25 (3H, t, J ) 7.0 Hz), 1.99-2.17 (2H, m), 2.21 (3H, s), 2.50 (2H, t, J ) 7.2 Hz), 3.54 (2H, s), 3.98 (2H, t, J ) 6.3 Hz), 4.14 (2H, q, J ) 7.0 Hz), 5.50 (1H, br s), 5.67 (1H, br s), 6.42 (1H, dd, J ) 8.2, 2.4 Hz), 6.73 (1H, d, J ) 2.4 Hz), 7.16 (1H, s), 7.27 (1H, d, J ) 8.2 Hz), 7.32-7.58 (5H, m); IR νmax (KBr) 2972, 2919, 1739, 1687, 1655, 1614 cm-1; EIMS m/z 115 (base peak), 405 (M+). Anal. (C25H27NO4‚0.9H2O) C, H, N. Ethyl [[1(Z)-benzylidene-3-(carbamoylmethyl)-2-methyl-1H-inden-4-yl]oxy]acetate (64b): 77% yield; mp 162-165 °C. Anal. (C23H23NO4‚0.8H2O) C, H, N. (Z)-Ethyl ((3-benzylidene-1-(carbamoylmethyl)-2-ethyl3H-inden-7-yl)oxy)acetate (64c): mp 139-142 °C; 61% yield. Anal. (C24H25NO4‚0.1H2O) C, H, N.

(Z)-Ethyl [[3-(biphenyl-2-ylmethylene)-1-(carbamoylmethyl)-2-ethyl-3H-inden-7-yl]oxy]acetate (64d): mp 161163 °C; 76% yield. Anal. (C30H29NO4‚1.5H2O) C, H, N. Ethyl (Z)-[[1-(2-benzylbenzylidene)-3-(carbamoylmethyl)-2-ethyl-1H-inden-4-yl]oxy]acetate (64e): mp 157.5158.5 °C; 83% yield. Anal. (C31H31 NO4‚0.4H2O) C, H, N. Ethyl (Z)-[[3-(carbamoylmethyl)-1-(3-chlorobenzylidene)-2-ethyl-1H-inden-4-yl]oxy]acetate (64f): mp 182.5184 °C; 57% yield. Anal. (C24H24 NO4Cl) C, H, N, Cl. Ethyl (Z)-[[3-(carbamoylmethyl)-1-(2,3-dichlorobenzylidene)-2-ethyl-1H-inden-4-yl]oxy]acetate (64g): mp 185.5-187.5 °C; 83% yield. Anal. (C24H23NO4Cl2) C, H, N, Cl. Ethyl (Z)-[[3-(carbamoylmethyl)-2-ethyl-1-(3-(trifluoromethyl)benzylidene)-1H-inden-4-yl]oxy]acetate (64h): mp 175.5-182.5 °C; 76% yield; EIMS m/z 400 (base peak), 459 (M+); HR-EIMS calcd for C25H24NO4F3 459.1656, found 459.1669. Ethyl (Z)-((3-(carbamoylmethyl)-2-ethyl-1-(naphthalen-1-ylmethylene)-1H-inden-4-yl)oxy)acetate (64i): mp 153.5-160 °C; 64% yield. Anal. (C28H27NO4‚0.4H2O) C, H, N. Ethyl (Z)-((3-(carbamoylmethyl)-2-ethyl-1-(naphthalen-2-ylmethylene)-1H-inden-4-yl)oxy)acetate (64j): mp 201-204 °C; 77% yield. Anal. (C28H27NO4‚0.8H2O) C, H, N. 4-[[1(Z)-Benzylidene-3-(carbamoylmethyl)-2-methyl1H-inden-5-yl]oxy]butanoic Acid (65a). NaOH (1 N, 0.200 mL, 0.200 mmol) was added to a solution of 64a (39.4 mg, 0.0972 mmol) in DMSO (1.0 mL) at room temperature. The solution was stirred at room temperature for 75 min and partitioned between 1 N HCl and AcOEt. The organic layer was separated, washed with water, dried, and evaporated. Recrystallization from AcOEt afforded 65a (19.5 mg, 53%): mp 187-188 °C; 1H NMR (d6-DMSO) δ 1.82-2.02 (2H, m), 2.14 (3H, s), 2.36 (2H, t, J ) 7.0 Hz), 3.94 (1H, t, J ) 6.3 Hz), 6.42 (1H, dd, J ) 8.4, 2.0 Hz), 6.85 (1H, d, J ) 2.0 Hz), 6.96 (1H, br s), 7.13 (1H, d, J ) 8.4 Hz), 7.16 (1H, s), 7.32-7.57 (6H, m); IR νmax (KBr) 3462, 3342, 1715, 1697, 1647, 1613, 1582 cm-1; EIMS m/z 232 (base peak), 377 (M+). Anal. (C23H23NO4‚0.5H2O) C, H, N. [[1(Z)-Benzylidene-3-(carbamoylmethyl)-2-methyl-1Hinden-4-yl]oxy]acetic acid (65b): mp 224-226 °C; 55% yield; EIMS m/z 349 (base peak, M+); HR-EIMS calcd for C21H19NO4 349.1312, found 349.1311. (Z)-((3-Benzylidene-1-(carbamoylmethyl)-2-ethyl-3Hinden-7-yl)oxy)acetic acid (65c): mp 119-205 °C; 91% yield; EIMS m/z 304 (base peak), 363 (M+); HR-EIMS calcd C22H21NO4 363.1469, found 363.1485. (Z)-[[1-(Biphenyl-2-ylmethylene)-3-(carbamoylmethyl)2-ethyl-1H-inden-4-yl]oxy]acetic acid (65d): mp 205-209 °C; 93% yield; Anal (C28H25NO4‚0.3H2O) C, H, N. (Z)-[[1-(2-Benzylbenzylidene)-3-(carbamoylmethyl)-2ethyl-1H-inden-4-yl]oxy]acetic acid (65e): mp 194-200 °C; quantitative yield; EIMS m/z 179 (base peak), 453 (M+); HREIMS calcd for C29H27NO4 453.1938, found 453.1944. (Z)-[[3-(Carbamoylmethyl)-1-(3-chlorobenzylidene)-2ethyl-1H-inden-4-yl]oxy]acetic acid (65f): mp 213.5-214 °C; 82% yield. Anal. (C22H20 NO4Cl‚0.3H2O) C, H, N, Cl. (Z)-[[3-(Carbamoylmethyl)-1-(2,3-dichlorobenzylidene)2-ethyl-1H-inden-4-yl]oxy]acetic acid (65g): mp 226-228.5 °C; 89% yield; EIMS m/z 378 (base peak), 431 (M+); HR-EIMS calcd for C22H19 NO4Cl2 431.0689, found 431.0685. (Z)-[[3-(Carbamoylmethyl)-2-ethyl-1-(3-(trifluoromethyl)benzylidene)-1H-inden-4-yl]oxy]acetic acid (65h): mp 207-211.5 °C; 70% yield. Anal. (C23H20 NO4F3) C, H, N, F. (Z)-((3-(Carbamoylmethyl)-2-ethyl-1-naphthalen-1-ylmethylene-1H-inden-4-yl)oxy)acetic acid (65i): mp 210.5213 °C; 90% yield; EIMS m/z 354 (base peak), 413 (M+); HREIMS calcd for C26H23NO4 413.1624, found 413.1621. (Z)-((3-(Carbamoylmethyl)-2-ethyl-1-naphthalen-2-ylmethylene-1H-inden-4-yl)oxy)acetic acid (65j): mp 210.5215.5 °C; 70% yield; EIMS m/z 354 (base peak), 413 (M+); HREIMS calcd for C26H23NO4 413.1626, found 413.1629. (Z)-Methyl ((3-Benzyl-1-(carbamoylmethyl)-2-ethyl3H-inden-7-yl)oxy)acetate (66a) and (Z)-Methyl ((3-Benzyl-1-(carbamoylmethyl)-2-ethyl-1H-inden-7-yl)oxy)-



acetate (67a). A mixture of the methyl ester of 65a (113 mg, 0.300 mmol) and 5% Pd-C (11.9 mg) in MeOH (5.0 mL) was hydrogenated under normal atmosphere for 18 min. The catalyst was filtered off and the solvent was evaporated. The residue was purified by preparative TLC (200 × 200 × 0.25 mm, eluting with AcOEt) to give the crude product which was recrystallized from CHCl3:hexane to afford the pure product 66a (48.8 mg, 43%): mp 118-121 °C; 1H NMR (300 MHz, CDCl3) δ 1.17 (3H, t, J ) 7.5 Hz), 2.40 (1H, qd, J ) 7.5, 15.0 Hz), 2.71 (1H, qd, J ) 7.5, 15.0 Hz), 2.78 (1H, dd, J ) 7.8, 13.8 Hz), 3.37 (1H, dd, J ) 4.2, 13.8 Hz), 3.56 (1H, d, J ) 15.3 Hz), 3.73 (1H, d, J ) 14.7 Hz), 3.72-3.83 (1H, m), 3.79 (3H, s), 4.65 (2H, s), 4.97 (1H, br s), 5.75 (1H, br s), 6.62 (1H, d, J ) 8.4 Hz), 6.76 (1H, d, J ) 7.2 Hz), 6.91-7.00 (2H, m), 7.01 (1H, t, J ) 7.8 Hz), 7.07-7.28 (3H, m); IR νmax (KBr) 3136, 3023, 1743, 1686 cm-1; EIMS m/z 334 (base peak), 379 (M+). Anal. (C23H25NO4) C, H, N. 67a: mp 183-186 °C; 1H NMR (300 MHz, CDCl3) δ 1.15 (3H, t, J ) 7.5 Hz), 2.62 (1H, qd, J ) 7.5, 15.0 Hz), 2.73 (1H, qd, J ) 7.5, 15.0 Hz), 2.89 (1H, dd, J ) 4.5, 13.8 Hz), 3.25 (1H, dd, J ) 5.3, 13.8 Hz), 3.80 (1H, s), 3.89-3.95 (3H, m), 4.72 (1H, ABq, A part J ) 16.7 Hz), 4.81 (1H, ABq, B part J ) 16.7 Hz), 4.90 (1H, br s), 5.97 (1H, br s), 6.48 (1H, d, J ) 8.1 Hz), 6.75 (1H, d, J ) 7.2 Hz), 7.11 (1H, t, J ) 7.8 Hz), 7.10-7.28 (5H, m); IR νmax (KBr) 3387, 3195, 1750, 1646 cm-1; EIMS m/z 334 (base peak), 379 (M+). (Z)-(3-Benzyl-1-(carbamoylmethyl)-2-ethyl-3H-inden7-yloxy)acetic acid (66b): 50% Yield, mp 193-197 °C (CHCl3:hexane). Anal. (C22H23NO4‚0.4H2O) C, H, N. (Z)-((3-Benzyl-1-(carbamoylmethyl)-2-ethyl-1H-inden7-yl)oxy)acetic acid (67b): 90% yield; EIMS m/z 231 (base peak), 365 (M+); HR-EIMS calcd for C22H23NO4 365.1626, found 365.1630. Enzyme Assay. Phospholipase A2 activity was measured by established procedures using racemic diheptanoylthiophosphatidylcholine/Triton mixed micelle (chromogenic assay)18 or 1-palmitoyl-2-oleoyl-sn-phosphatidylcholine/deoxycholic acid mixed micelle (PC/DOC assay)19,20 as substrate. Chromogenic Assay. A 200 µL portion of the reaction mixture containing 1 mM diheptanoylthiophosphatidylcholine, 0.3 mM Triton, 0.12 mM DTNB, 10 mM CaCl2, 0.1 M KCl, and 0.1% BSA in 25 mM Tris-HCl buffer (pH 7.5) was added to the wells of a microplate. Test compounds (10 µL) were added to each well as DMSO solutions. To the control wells was added 10 µL of DMSO. Reactions were initiated by addition of 50 ng of the enzyme in 10 µL of AcONa buffer (pH 4.5) containing 0.2 M NaCl and incubated at 40 °C for 30 min. The reaction was monitored by the absorbance of wells at 405 nm with an automatic plate reader. The IC50 values were determined by diluting test compounds serially 5-fold. Inhibition measured at 405 nm, generated by enzyme reactions containing inhibitors relative to the uninhibited control reactions, was determined. Each sample was titrated in triplicate, and result values were averaged for plotting and calculation of IC50 values. IC50 values were determined by plotting log concentration versus inhibition values in the range from 10 to 90% inhibition. PC/DOC Assay. A 160 µL portion of the reaction mixture containing 1 mM 1-palmitoyl-2-oleoylphosphatidylcholine, 3 mM sodium deoxycholic acid, 10 mM CaCl2, 150 mM NaCl, and 0.1% BSA in 100 mM Tris-HCl buffer (pH 8.0) was added to the test tube. Test compounds (20 µL) were added to each tube as DMSO solution and preincubated at 40 °C for 10 min. Reactions were initiated by addition of 20 ng of the enzyme in 20 µL of AcONa buffer (pH 4.5) containing 0.2 M NaCl and incubated at 40 °C for 30 min. Reactions were stopped by addition of 800 µL of Dole reagent.22 Margaric acid (6 nM) in heptane (12 µL) was added as an internal standard. Then 320 µL of distilled water and 480 µL of heptane were added, and the solution was shaken for 10 s. After centrifugation at 20 °C for 30 s at 10 000 rpm, 400 µL of the upper phase was pipetted into another tube containing 15-20 mg of silicic acid powder, and then the solution was shaken for 30 s. After centrifugation for 30 s at 10 000 rpm, 150 µL of heptane was transfered into another tube, and the heptane was removed using a water aspirator. Then 100 µL of 0.05% 9-anthryldia-

zomethane solution was added. The mixture was incubated for 15 min at room temperature. An aliquot (10-15 µL) of the mixture was injected onto a Supersphere RP-8 column and eluted with 93% CH3CN. The amount of released oleic acid was calculated by the ratio to margaric acid. Each sample was titrated in duplicate, and the values were averaged for plotting and calculation of IC50 values. Inhibition generated by enzyme reactions containing inhibitors relative to the uninhibited control reactions were calculated. IC50 values were determined by plotting log concentration versus inhibition values in the range from 10 to 90% inhibition.

Acknowledgment. We would like to acknowledge our colleagues at Lilly Research Laboratories, Indianapolis, IN, who have collaborated with us during the course of this project. We thank Drs. H. Arita and Y. Hori for their support asd suggestions throughout the course of this work. References (1) (a) Mayer, R. J.; Marshall, L. A. New Insights on Mammalian Phopspholipase A2(s); Comparison of Arachidonoyl-Selective and -Non Selective Enzymes. FASEB J. 1993, 7, 339-348. (b) Bomalaski, J. S.; Clark, M. A. Phospholipase A2 and Arthritis. Arthritis Rheumatism 1993, 36, 190-198. (2) (a) Vadas, P.; Pruzanski, W.; Stefanski, E.; Ruse, J.; Farewell, V.; McLaughlin, J.; Bombardier, C. Concordance of Endogeneous Cortisol and Phospholipase A2 Levels in Gram-Negative Septic Shock: A Prospective Study. J. Lab. Clin. Med. 1988, 111, 584. (b) Aufenanger, J.; Zimmer, W.; Kattermann, R. Characteristics and Clinical Application of a Radiometric Escherichia Coli-Based Phospholipase A2 Assay Modified for Serum Analysis. Clin. Chem. 1993, 39, 605-613. (3) Nevalainen, T. J. The role of phospholipase A in acute pancreatitis. Scand. J. Gastroenterol 1980, 15, 641-650. (4) (a) Vadas, P.; Pruzanski, W. Role of Secretory Phospholipase A2 in the Pathobiology of Disease. Lab. Invest. 1986, 55, 391-404. (b) Pruzanski, W.; Vadas, P. Secretory Synovial Fluid Phosphlipase A2 and its Role in the Pathogenesis of Inflammation in Athritis. J. Rheumatol. 1988, 15, 1601-1603. (c) Pruzanski, W., Vadas, P. Phospholipase A2: A Mediator Between Proximal and Distal Effectors of Inflammation. Immunol. Today 1991, 12, 143-146. (5) (a) Mobilio, D.; Marshall, L. A. Recent Advances in the Design and Evaluation of Inhibitors of PLA2. Annu. Rep. Med. Chem. 1989, 24, 157-166. (b) Sofia, M. J.; Silbough, S. A. Novel Approaches to Anti-Inflammatory Agents as Therapeutics for Pulmonary Disease. Annu. Rep. Med. Chem. 1993, 28, 109-118. (c) Wilkerson, W. W. Anti-Inflammatory Phospholipase A2 Inhibitors. Drugs Future 1990, 15, 139-148. (6) Schevitz, R. V.; Bach, N. J.; Carlson, D. G.; Chirgadze, N. Y.; Carlson, D. K.; Dillard, R. D.; Draheim, S. E.; Hartley, L. W.; Jones, N. D.; Mihelich, E. D.; Olkowski, J. L.; Snyder, D. W.; Sommers, C.; Wery, J.-P. Structure-Based Design of the First Potent and Selective Inhibitor of Human non-Pancreatic Secretory Phospholipase A2. Nature Struct. Biol. 1995, 2, 458-465 (7) Marison, L.; Cockburn, W. F. The synthesis of pseudoconhydrine. J. Am. Chem. Soc. 1949, 71, 3402-3404. (8) Konakahara, T.; Takagi, Y. Convenient method for the preparation of 2-phenacylpyridines. Heterocycles 1980, 14, 393-396. (9) (a) Uchida, T.; Matsumoto, K. Methods for the construction of the indolizine nucleus. Synthesis 1976, 209-236. (b) Casagrande, C.; Invernizzi, A.; Ferrini, R.; Miragoli, G. Indolizine analogues of indomethacin. Farmaco. Ed. Sci. 1971, 26, 1059-1073. (10) (a) Desidiri, N.; Galli, A.; Seslili, I.; Stein, M. l. Synthesis and binding properties to GABA receptors of 3-hydroxypyridyl- and 3-hydroxypiperidyl- analogues of Baclofen. Arch. Pharm. 1992, 325, 29-33. (b) Kimura. E.; Kotake, Y.; Koike, T.; Shionoya, M.; Shiro, M. A novel cyclam appended with 3-hydroxypyridine. An ambient donor ligand comprising a pyridyl N and apyridynolate O- donor. Inorg. Chem. 1990, 29, 4991-4996. (11) Lau, C. K.; Tardif, S.; Dufresne, C.; Scheigetz, J. Reductive deoxygenation of aryl aldehydes and ketones by tert-butylamineborane and aluminum chloride. J. Org. Chem. 1989, 54, 491494. (12) Desideri, N.; Manna, F.; Stein, M. L.; Bile, G.; Filippelli, W.; Marmo, E. Eur. Synthesis of 3-hydroxy-2-pyridineacetic acid and its evaluation on experimentallipaemia. J. Med. Chem. 1983, 18, 295-299. (13) Bellesia, F.; Ghelfi, F.; Grandi, R.; Pagnoni, U. M. Regioselective R-bromination of carbonyl compounds with trimethylbromosilane-dimethylsulfoxide. J. Chem. Res. (s) 1986, 428-429.

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(14) (a) Rapport, H.; Volcheck jr., E. J. The synthesis of desoxycarpyrinic and carprinic acids. J. Am. Chem. Soc. 1956, 78, 24512455. (b) Iorio, M. A.; Gatta, F.; Michalek, H. Synthesis and conformational aspects of acetoxypiperidinium iodides related to acetylcholine. Eur. J. Med. Chem. 1980, 15, 165-171. (15) Flitsh, W. Pyrroles with fused six-membered heterocyclic rings: (i) a-fused. Comprehensive Heterocyclic Chemistry; Bird, C. W., Cheesman, G. W. M., Eds.; Pergamon Press: London. 1984; Vol. 4, pp 443-495. (16) Kakehi, A.; Ito, S.; Yamada, N.; Yamaguchi, K. Preparation of new nitrogen-bridged heterocycles. 21. A facile synthesis of 2-indolizinethiols using new protecting groups. Bull. Chem. Soc. Jpn. 1990, 63, 829-834. (17) Gresham, T. L.; Jansen, J. E.; Shaver, F. W.; Bankart, R. A.; Beears, W. L.; Prendergast, M. G. β-Propiolactone. VI. Reactions with phenols, thiophenols and their salts. J. Am. Chem. Soc. 1949, 71, 661-663. (18) Reynolds, L. J.; Hughes, L. L.; Dennis, E. A. Analysis of human synovial fluid phospholipase A2 on short chain phosphatidyl-

Hagishita et al.

(19)

(20)

(21)

(22)

choline-mixed micelles: development of a spectrometric assay suitable for a microtiterplate reader. Anal. Biol. 1992, 204, 190197. Schadlich, H. R.; Buchler, M.; Berger, H. G. Improved method for the determination of phospholipase A2 catalytic concentration in human serum and ascities. J. Clin. Chem. Clin. Biochem. 1987, 25, 505-509. Tojo, H.; Ono, T.; Okamoto M. Reverse-phase high performance liquid chromatographic assay of phospholipases: application of spectrometric detection to rat phospholiase A2 isozymes J. Lipid Res. 1993, 34, 837-844. Hamanaka, Y.; Fukushima, S.; Hiyama, T. a convenient synthesis of substituted heteroaromatic compounds via the palladium-catalyzed cross-coupling reaction of organosilicon compounds. Heterocycles 1990, 30, 303-306. Dole, V. P.; Meinertz, H. J. Microdetermination of long-chain fatty acids in plasma and tissues. J. Biol. Chem. 1960, 235, 2595-2599.

JM960395Q

Potent Inhibitors of Secretory Phospholipase A2: Synthesis and

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